Semiconductor light-emitting device and method for manufacturing same

ABSTRACT

A semiconductor light-emitting device includes: a laminated structure, a first electrode, a second electrode and a dielectric laminated film. The laminated structure includes, a first semiconductor layer, a second semiconductor layer, and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer, in which the second semiconductor layer and the light-emitting layer are selectively removed and a part of the first semiconductor layer is exposed to a first main surface on the side of the second semiconductor layer. The first electrode is provided on the first main surface of the laminated structure and connected to the first semiconductor layer and has a first region including a first metal film provided on the first semiconductor layer of the first main surface, and a second region including a second metal film provided on the first semiconductor layer and having a higher reflectance for light emitted from the light-emitting layer than the first metal film and having a higher contact resistance with respect to the first semiconductor layer than the first metal film. The second electrode is provided on the first main surface of the laminated structure and connected to the second semiconductor layer. The dielectric laminated film is provided on the first and second semiconductor layer being not covered with the first and second electrode and has a plurality of dielectric films having different refractive indices being laminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/400,396, filed on Mar. 9, 2009, which claims the benefit of priorityto Japanese Patent Application No. 2008-220143, filed on Aug. 28, 2008,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to a semiconductor light-emitting device and amethod for manufacturing the same.

BACKGROUND ART

Light generated in a semiconductor light-emitting device such as LED(Light Emitting Diode) is directly taken out of the device, or taken outfrom a device surface or a substrate surface or a side surface of thedevice by repeating reflection inside the semiconductor light-emittingdevice such as a reflection film, an interface between a semiconductorlayer and a substrate, or an interface between a substrate and ambientair. Some of the light inside the device is absorbed by an n-sideelectrode having low reflection efficiency, and some of the light takenout of the device is absorbed by a mount material or the like, and theseare factors of lowering the light extraction efficiency.

An effective method for enhancing the light extraction efficiency istaking out the light emitted inside the device to the direction in whichan absorber such as the mount material does not exist by ingenuity ofthe device shape or the reflection film or the like. On the other hand,the area of the n-side electrode which is an absorber inside the deviceis required to be large to a certain extent from the constraint on theelectrode design such as, wire bonding by ball bonding or the like,formation of bump for a flip chip, and reduction of voltage drop due tothe contact resistance of the n-side electrode. Moreover, in the case ofthe device in which the reflection film is combined with the p-sideelectrode, the area of the reflection film cannot be freely enlargedfrom the constraint on the design of the light-emitting region or theelectrode design such as the combination with the n-side electrode.

On the other hand, there has been disclosed a technique in which asemiconductor device made of nitride semiconductor having few crystaldefects is provided by forming a nitride semiconductor of high qualityon a substrate (Patent document 1: JP-A 2000-31588 (Kokai)). If there isa layer having a large number of crystal defects, the light emitted froma light-emitting layer is absorbed and the loss is caused, but by usingsuch a technique as disclosed in JP-A 2000-31588 (Kokai), the absorbanceinside the device for the light emitted from the light-emitting layercan be suppressed.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided asemiconductor light-emitting device including: a laminated structureincluding, a first semiconductor layer, a second semiconductor layer,and a light-emitting layer provided between the first semiconductorlayer and the second semiconductor layer, the second semiconductor layerand the light-emitting layer being selectively removed and a part of thefirst semiconductor layer being exposed to a first main surface on aside of the second semiconductor layer; a first electrode provided onthe first main surface of the laminated structure and connected to thefirst semiconductor layer and having a first region including a firstmetal film provided on the part of the first semiconductor layer and asecond region including a second metal film provided on the part of thefirst semiconductor layer, the second region having a higher reflectancefor light emitted from the light-emitting layer than the first metalfilm and the second region having a higher contact resistance withrespect to the first semiconductor layer than the first metal film; asecond electrode provided on the first main surface of the laminatedstructure and connected to the second semiconductor layer; and adielectric laminated film provided on the first semiconductor layer andthe second semiconductor layer being not covered with any one of thefirst electrode and the second electrode on the first main surface, thedielectric laminated film having a plurality of dielectric films havingdifferent refractive indices being laminated.

According to another aspect of the invention, there is provided a methodfor manufacturing a semiconductor light-emitting device including:laminating a first semiconductor layer, a light-emitting layer, and asecond semiconductor layer, on a substrate; removing a part of thesecond semiconductor layer and the light-emitting layer being configuredto expose the first semiconductor layer; forming a first metal film on afirst region of the exposed first semiconductor layer; forming a secondmetal film having a higher reflectance for light emitted from thelight-emitting layer than the first metal film and having a highercontact resistance with respect to the first semiconductor layer thanthe first metal film, on a second region adjacent to the first region ofthe exposed first semiconductor layer and on the second semiconductorlayer; and forming a dielectric laminated film by alternately laminatingdielectric films having different refractive indices on the first metalfilm and the second metal film being not covered with the firstelectrode and the second electrode.

According to another aspect of the invention, there is provided A methodfor manufacturing a semiconductor light-emitting device, including:laminating a first semiconductor layer, a light-emitting layer, and asecond semiconductor layer, on a substrate; removing a part of thesecond semiconductor layer and the light-emitting layer being configuredto expose the first semiconductor layer; selectively forming adielectric laminated film by alternately laminating dielectric filmshaving different refractive indices on the first semiconductor layer andthe second semiconductor layer; and forming a first metal film on afirst region of the first semiconductor layer being not covered with thedielectric laminated film, and forming a second metal film having ahigher reflectance for light emitted from the light-emitting layer thanthe first metal film and having a higher contact resistance with respectto the first semiconductor layer than the first metal film, on a secondregion of the first semiconductor layer being adjacent to the firstregion and being covered with the dielectric laminated film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic views illustrating the configuration of asemiconductor light-emitting device according to a first embodiment ofthe invention;

FIGS. 2A and 2B are schematic cross-sectional views illustrating theconfiguration of a semiconductor light-emitting device of comparativeexample;

FIG. 3 is a schematic plan view showing a modified example of thesemiconductor light-emitting device according to the first embodiment ofthe invention;

FIG. 4 is a schematic plan view showing a modified example of thesemiconductor light-emitting device according to the first embodiment ofthe invention;

FIGS. 5A and 5B are graphic views illustrating characteristics of thesemiconductor light-emitting device according to the first embodiment ofthe invention;

FIG. 6 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to asecond embodiment of the invention;

FIGS. 7A to 7C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the second embodiment of the invention;

FIGS. 8A to 8C are schematic cross-sectional views by step sequencefollowing FIGS. 7A to 7C;

FIG. 9 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to athird embodiment of the invention;

FIG. 10 is a schematic cross-sectional view illustrating theconfiguration of another semiconductor light-emitting device accordingto the third embodiment of the invention;

FIG. 11 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to afourth embodiment of the invention;

FIG. 12 is a graphic view illustrating a characteristic of thesemiconductor light-emitting device according to the fourth embodimentof the invention;

FIG. 13 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to afifth embodiment of the invention;

FIGS. 14A to 14C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the fifth embodiment of the invention;

FIGS. 15A to 15C are schematic cross-sectional views by step sequencefollowing FIGS. 14A to 14C;

FIG. 16 is a schematic cross-sectional view by step sequence followingFIGS. 15A to 15C;

FIG. 17 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to asixth embodiment of the invention;

FIGS. 18A to 18C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the sixth embodiment of the invention;

FIGS. 19A to 19C are schematic cross-sectional views by step sequencefollowing FIGS. 18A to 18C;

FIG. 20 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aseventh embodiment of the invention;

FIGS. 21A to 21C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the seventh embodiment of the invention;

FIGS. 22A to 22C are schematic cross-sectional views by step sequencefollowing FIGS. 21A to 21C;

FIG. 23 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aneighth embodiment of the invention;

FIGS. 24A to 24C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the eighth embodiment of the invention;

FIG. 25 is a schematic cross-sectional view by step sequence followingFIGS. 24A to 24C;

FIG. 26 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aninth embodiment of the invention;

FIG. 27 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to atenth embodiment of the invention;

FIG. 28 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aneleventh embodiment of the invention;

FIG. 29 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to atwelfth embodiment of the invention;

FIGS. 30A to 30C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the twelfth embodiment of the invention;

FIGS. 31A to 31C are schematic cross-sectional views by step sequencefollowing FIGS. 30A to 30C;

FIG. 32 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to athirteenth embodiment of the invention;

FIGS. 33A to 33C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the thirteenth embodiment of the invention;

FIGS. 34A to 34C are schematic cross-sectional views by step sequencefollowing FIGS. 33A to 33C;

FIG. 35 is a flow chart illustrating a method for manufacturing thesemiconductor light-emitting device according to a fourteenth embodimentof the invention;

FIG. 36 is a flow chart illustrating a method for manufacturing thesemiconductor light-emitting device according to a fifteenth embodimentof the invention;

FIG. 37 is a flow chart illustrating a modified example of the methodfor manufacturing the semiconductor light-emitting device according tothe fifteenth embodiment of the invention; and

FIG. 38 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting apparatus according to asixteenth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the invention will be described withreference to drawings.

The drawings are schematic or conceptual, and a relation between athickness and a width of each of parts or a ratio coefficient of sizesof parts or the like is not necessarily the same as the real one.Moreover, even if the same part is shown, occasionally, each of thesizes or the ratio coefficient is shown to be different according to thedrawings.

Moreover, in this specification and each of the drawings, the samenumerals are appended to the same components as described above withrespect to a previous figure, and the detailed description thereof willbe appropriately omitted.

First Embodiment

FIG. 1 is a schematic view illustrating the configuration of asemiconductor light-emitting device according to a first embodiment ofthe invention.

That is, FIG. 1B is a plan view, and FIG. 1A is a cross-sectional viewtaken along the line A-A′ of FIG. 1B.

As shown in FIG. 1A, in the semiconductor light-emitting device 101according to the first embodiment of the invention, a laminatedstructure 1 s in which an n-type semiconductor layer (firstsemiconductor layer) 1, a light-emitting layer 3, and a p-typesemiconductor layer (second semiconductor layer) 2 are laminated in thisorder on a substrate 10 made of, for example, sapphire is formed.

And, on the side of a main surface 1 a of this laminated structure 1 s,a p-side electrode (second electrode) 4, an n-side electrode (firstelectrode) 7 and a dielectric laminated film 11 are provided.

The p-side electrode 4 is provided on the side of the main surface 1 aof the p-type semiconductor layer 2. The p-side electrode 4 can have asecond p-side electrode film 4 b serving as a high-efficiency reflectionfilm and a first p-side electrode film 4 a made of metal that does notnecessarily require the high-efficiency reflection characteristics asdescribed later.

Furthermore, part of the p-type semiconductor layer 2 is etched byetching, and the n-side electrode 7 is provided on the side of the mainsurface 1 a of the exposed n-type semiconductor layer 1. And, the n-sideelectrode 7 has a second n-side electrode film (second metal film) 7 bserving as a high-efficiency reflection film and a first n-sideelectrode film (first metal film) 7 a serving as an ohmic contactregion.

And, the dielectric laminated film 11 is provided on the p-typesemiconductor layer 2 and the n-type semiconductor layer 1 being notcovered with the p-side electrode 4 and the n-side electrode 7. In thedielectric laminated film 11, two or more layers of two or more kinds ofdielectric materials having different refractive indices are laminated.However, in the peripheral portion of the device, the dielectriclaminated film 11 may be removed, and in the peripheral portion of thedevice, the dielectric laminated film 11 may be damaged.

For the dielectric laminated film 11, as the two or more kinds ofdielectric materials having different refractive indices, five groups ofthe combination of the laminated film of a first dielectric layer (suchas SiO₂) and a second dielectric layer (such as TiO₂), namely, thelaminated film composed of ten dielectric layers in total can be used.In this case, the thickness of each of the first dielectric layer andthe second dielectric layer is set to be λ/(4n), where n is a refractiveindex of each of the dielectric layers and λ is an emission wavelengthfrom the light-emitting layer 3.

That is, the dielectric laminated film 11 is composed of a firstdielectric layer having a first refractive index n₁ and a seconddielectric layer having a second refractive index n₂ that is differentfrom the first refractive index n₁ which are alternately laminated, andwhen an emission wavelength of the light-emitting layer 3 is λ, athickness of each of the first dielectric layers is substantiallyλ/(4n₁) and a thickness of each of the second dielectric layers issubstantially λ/(4n₂).

Thereby, the emitted light from the light-emitting layer 3 can bereflected efficiently and reflected to the semiconductor layer side.

That is, the semiconductor light-emitting device 101 according to thisembodiment includes: a laminated structure 1 s including, a firstsemiconductor layer (n-type semiconductor layer 1), a secondsemiconductor layer (p-type semiconductor layer 2), and a light-emittinglayer 3 provided between the first semiconductor layer and the secondsemiconductor layer; a first electrode (n-side electrode 7) provided ona first main surface 1 a of the laminated structure is and connected tothe first semiconductor layer and having, a first region 8 a including afirst metal film (first p-side electrode film 7 a) provided on the firstsemiconductor layer, and a second region 8 b including a second metalfilm (second n-side electrode film 7 b) that is provided on the firstsemiconductor layer and that has a higher reflectance for light emittedfrom the light-emitting layer than the first metal film and that has ahigher contact resistance with respect to the first semiconductor layerthan the first metal film; a second electrode (p-side electrode 4)provided on the first main surface 1 a of the laminated structure 1 sand connected to the second semiconductor layer; and a dielectriclaminated film 11 provided on the first semiconductor layer and thesecond semiconductor layer that are not covered with the first electrodeand the second electrode on the first main surface 1 a, in which aplurality of combinations having a plurality of dielectric films havingdifferent refractive indices are laminated.

In the semiconductor light-emitting device 101 according to thisembodiment, by providing the second n-side electrode film 7 b serving asa high-efficiency reflection film in the n-side electrode 7, the lightemitted from the light-emitting layer 3 can be reflected with highefficiency and taken out of the device. That is, the light extractionefficiency of the semiconductor light-emitting device can be improved.

The second n-side electrode film 7 b may be a single-layer of silver oraluminum, or may be an alloy layer containing silver or aluminum andmetal other than them. The reflection efficiency of a normalsingle-layer metal film for the visible band tends to lower as itswavelength is shorter, but silver and aluminum have high reflectionefficiency characteristics also for light in the ultraviolet band from370 nm to 400 nm inclusive.

Therefore, when the second n-side electrode film 7 b is made of silveror an aluminum alloy in the semiconductor light-emitting device forultraviolet emission, it is preferable that the second n-side electrode7 b on the semiconductor interface side has a higher component ratio ofsilver or aluminum.

Moreover, it is preferable that the film thickness of the second n-sideelectrode film 7 b is 100 nm or more for ensuring the light reflectionefficiency.

On the other hand, the first n-side electrode film 7 a serving as theohmic contact region has a role of reducing the contact resistance withrespect to the n-type semiconductor layer 1 and lowering the deviceresistance to pass a current.

The material of the first n-side electrode film 7 a formed in the regionhaving ohmic characteristics is not particularly limited, but composedof a single-layer or multilayer conductive film used as an ohmicelectrode of the n-type semiconductor layer 1. The film thickness of thefirst n-side electrode film 7 a is not particularly limited, but can beselected in the range of 5 nm to 1000 nm.

By performing the design so that the layer structure of the dielectriclaminated film 11 has high-efficiency reflection characteristics for theemitted light, the reflection area of the electrode-formed surface canbe enlarged drastically while holding the insulation of the p-sideelectrode 4 and the n-side electrode 7 without making particularingenuity on the process. That is, the light extraction efficiency ofthe semiconductor light-emitting device can be improved.

According to the semiconductor light-emitting device 101 having such aconfiguration, while achieving the n-side electrode 7 ensuring the ohmiccontact with the n-type semiconductor layer 1 and having an arearequired for formation of wire bonding or bump or the like, thesemiconductor light-emitting device can be obtained, in which almost allof the region other than the first n-side electrode film 7 a in theelectrode-formed surface as a reflection region.

In the specific example shown in FIG. 1B, the n-side electrode 7occupies a corner of the semiconductor light-emitting device having aquadrangular shape, but the shape of the n-side electrode 7 is notlimited thereto.

Moreover, in FIG. 1B, the dielectric laminated film 11 is omitted.

Next, a specific example of a laminated structure of the semiconductorlayer formed on the substrate 10 will be described.

The semiconductor light-emitting device 101 according to this embodimentis composed of nitride semiconductors formed on the substrate 10 madeof, for example, sapphire.

That is, there can be adopted a structure in which a first AlN bufferlayer with high carbon concentration (the carbon concentration is 3×10¹⁸cm⁻³ to 5×10²⁰ cm⁻³) with a thickness of 3 nm to 20 nm, a second AlNbuffer layer of high purity (the carbon concentration is 1×10¹⁶ cm⁻³ to3×10¹⁸ cm⁻³) with a thickness of 2 μm, a non-doped GaN buffer layer witha thickness of 3 μm, a Si-doped n-type GaN contact layer (the Siconcentration is 1×10¹⁸ cm⁻³ to 5×10¹⁸ cm⁻³) with a thickness of 4 μm, aSi-doped n-type Al_(0.10)Ga_(0.90)N cladding layer with a thickness of0.02 μm (the Si concentration is 1×10¹⁸ cm⁻³), a light-emitting layerwith a thickness of 0.075 μm having a multiple quantum well structure inwhich a Si-doped n-type Al_(0.11)Ga_(0.89)N barrier layer (the Siconcentration is 1.1-1.5×10¹⁹ cm⁻³) and a GaInN light-emitting layer(the wavelength is 380 nm) are laminated alternately in three periods, afinal Al_(0.11)Ga_(0.89)N barrier layer of the multiple quantum well(the Si concentration is 1.1-1.5×10¹⁹ cm⁻³) with a thickness of 0.01 μm,a Si-doped n-type Al_(0.11)Ga_(0.89)N layer (the Si concentration is0.8-1.0×10¹⁹ cm⁻³) with a thickness of 0.01 μm, a non-dopedAl_(0.11)Ga_(0.89)N spacer layer with a thickness of 0.02 μm, a Mg-dopedp-type Al_(0.28)Ga_(0.72)N cladding layer with a thickness of 0.02 μm(the Mg concentration is 1×10¹⁹ cm⁻³), a Mg-doped p-type GaN contactlayer (the Mg concentration is 1×10¹⁹ cm⁻³) with a thickness of 0.1 μm,and a high-concentration-Mg-doped p-type GaN contact layer (the Mgconcentration is 2×10²⁰ cm⁻³) with a thickness of 0.02 μm aresequentially laminated using, for example, metal organic chemical vapordeposition on the substrate 10 whose surface is a sapphire c plane.

Here, the n-type semiconductor layer 1 illustrated in FIG. 1A caninclude the first AlN buffer layer with high carbon concentration, thesecond AlN buffer layer of high purity, the non-doped GaN buffer layer,the Si-doped n-type GaN contact layer, and the Si-doped n-typeAl_(0.10)Ga_(0.90)N cladding layer.

Moreover, the light-emitting layer 3 illustrated in FIG. 1A can include,the light-emitting layer having a multiple quantum well structure inwhich the Si-doped n-type Al_(0.11)Ga_(0.89)N barrier layer and theGaInN light-emitting layer (the wavelength is 380 nm) are laminatedalternately in three periods, and the final Al_(0.11)Ga_(0.89)N barrierlayer of the multiple quantum well.

And, the p-type semiconductor layer 2 illustrated in FIG. 1A can includethe Mg-doped p-type Al_(0.28)Ga_(0.72)N cladding layer, the Mg-dopedp-type GaN contact layer, and the high-concentration-Mg-doped p-type GaNcontact layer.

By setting the Mg concentration of the high-concentration-Mg-dopedp-type GaN contact layer to be in the order of 1×10²⁰ cm⁻³, which isslightly high, the ohmic contact with the p-side electrode can beimproved. However, in the case of a semiconductor light-emitting diode,differently from a semiconductor laser diode, the distance between theabove contact layer and the light-emitting layer is short, andtherefore, degradation of the characteristic due to Mg diffusion isfeared. Accordingly, by utilizing that the contact area between thep-side electrode 4 and the above contact layer is large and that thecurrent density during operation is low, the above Mg concentration canbe suppressed to be in the order of 1×10¹⁹ cm⁻³ without largely damagingelectrical characteristics to prevent the diffusion of Mg and improvelight emission characteristics.

The first AlN buffer layer with high carbon concentration functions torelax the difference of the crystal types from the substrate, andparticularly, reduces screw dislocation.

Moreover, in the second AlN buffer layer with high purity, its surfaceis planarized at the atomic level. Therefore, defects of the non-dopedGaN buffer layer grown thereon are reduced, and to this end, it ispreferable that the film thickness of the second AlN buffer layer withhigh purity is thicker than 1 μm. Moreover, for preventing warpage dueto strain, it is desirable that the thickness of the second AlN bufferlayer of high purity is 4 μm or less. The second AlN buffer layer withhigh purity is not limited to AlN, but Al_(x)Ga_(1-x)N (0.8≦x≦1) ispossible to compensate warpage of the wafer.

Moreover, the non-doped GaN buffer layer serves to reduce defects by3-dimensional island growth on the second AlN buffer layer with highpurity. For the planarization of the growth surface, it is necessarythat the average film thickness of the non-doped GaN buffer layer is 2μm or more. From the viewpoints of reproducibility and lowering ofwarpage, it is appropriate that the total film thickness of thenon-doped GaN buffer layer is 4 to 10 μm.

By adopting these buffer layers, in comparison to a conventionallow-temperature growth AlN buffer layer, the defects can be reduced byabout 1/10. By this technique, despite high-concentration Si-doping tothe n-type GaN contact layer or light emission in the ultraviolet band,the semiconductor light-emitting device with high efficiency can befabricated. Moreover, by reducing the crystal defects in the bufferlayers, light absorption in the buffer layers can also be suppressed.

And, according to the semiconductor light-emitting device 101 of thisembodiment, the second n-side electrode film 7 b having high reflectanceis provided in the n-side electrode 7, and furthermore, the dielectriclaminated film 11 is provided, and thereby, the light emitted from thelight-emitting layer 3 can be reflected with high efficiency and takenout of the device.

Comparative Example

FIGS. 2A and 2B are schematic cross-sectional views illustrating theconfiguration of a semiconductor light-emitting device of comparativeexample.

As shown in FIGS. 2A and 2B, in the semiconductor light-emitting device90 of the comparative example, the n-side electrode 7 is made of asingle metal layer. And, the dielectric laminated film 11 is not formed.That is, instead of the dielectric laminated film 11, as a single-layerdielectric film, which is not shown, made of, for example, SiO₂ of 400nm is formed.

Hereinafter, a method for manufacturing the semiconductor light-emittingdevice 90 of the comparative example will be described.

First, for forming the p-side electrode 4, a patterned lift-off resistis formed on the semiconductor layer, and part of the p-side electrode 4made of Ag is formed with a film thickness of 200 nm on the p-typecontact layer using a vacuum deposition apparatus, and sintered in anitrogen atmosphere at 350° C. after the lift-off.

Similarly, a patterned lift-off resist is formed on the semiconductorlayer, and on the n-type contact layer, a Ti/Pt/Au layer serving as then-side electrode 7 is formed with a film thickness of 500 nm. Similarly,a patterned lift-off resist is formed on the semiconductor layer, and aPt/Au layer serving as another part of the p-side electrode 4 is formedwith a film thickness of 500 nm so as to cover the region in which theAg layer serving as part of the p-side electrode 4 is formed.

Thus, the electrodes of the semiconductor light-emitting device 90 ofComparative example are composed.

In the semiconductor light-emitting device 90 of Comparative example,the entire surface of the n-side electrode 7 is formed from a metal forohmic contact. In the case of using such a metal, the reflectance is notnecessarily sufficiently high. Furthermore, in the ohmic contact region,reaction (alloying) is easily caused between the n-side electrode 7 andthe n-type semiconductor layer 1, and this is also a factor of loweringthe reflectance for the light. Moreover, in the case of mounting themain surface side having the electrodes formed on a submount or thelike, the emitted light incident to the region in the main surface onwhich the p-side electrode 4 is not formed is absorbed by the mountmaterial. Hence, there is room for improvement in terms of theextraction efficiency for the light emitted from the light-emittinglayer 3.

By contrast, as described previously, in the semiconductorlight-emitting device 101 according to this embodiment, by forming partof the n-side electrode 7 from the second n-side electrode film 7 bhaving high reflectance and adopting the dielectric laminated film 11having high reflection characteristics, the almost entire surface of themain surface 1 a of the semiconductor layer in which the electrodes areformed is set to be a reflection structure, and thereby, the lightextraction efficiency can be improved.

In the semiconductor light-emitting device 101 according to thisembodiment, the current flowing between the p-side electrode 4 and then-side electrode 7 tends to flow through the closest portiontherebetween.

Accordingly, as in the specific example shown in FIGS. 1A and 1B, byplacing the first n-side electrode film 7 a nearer to the p-sideelectrode 4 than the second n-side electrode film 7 b, the current canbe passed more reliably between the p-side electrode 4 and the n-sideelectrode 7 even if the area of the first n-side electrode film 7 aserving as an ohmic contact region is small.

As described above, the first n-side electrode film 7 a can be providedin a portion of the n-side region 7 facing the p-side electrode 4.

That is, the portion of the n-side electrode 7 facing the p-sideelectrode 4 that is a region on which the current is relativelyconcentrated during energization is formed from the first n-sideelectrode film 7 a having low contact resistance, and thereby, influenceon electrical characteristics exerted by forming a high-efficiencyreflection film (second n-side electrode film 7 b) that does notnecessarily have low contact resistance in the n-side electrode 7 can besuppressed to the minimum.

With regard to the current path from the second electrode 4 to the firstn-side electrode film 7 a of the n-side electrode, the current tends toconcentrate on the region with the shortest distance between the secondelectrode 4 and the first n-side electrode film 7 a, and hence, forrelaxing the electric field concentration, it is preferable that theregion with the above shortest distance out of the region in which thesecond electrode 4 faces the first n-side electrode film 7 a is designedto be as long as possible.

Moreover, in plan view, as the length of the region in which the secondelectrode 4 faces the first n-side electrode film 7 a increases, thenumber of current paths from the second electrode 4 to the first n-sideelectrode film 7 a increases, and hence, the electric fieldconcentration is relaxed, and the degradation of the second electrode 4is suppressed. By considering these effects, the area and shape of thesecond n-side electrode film 7 b and the first n-side electrode film 7 aand the area and shape of the entire n-side electrode 7 can beappropriately determined.

According to the semiconductor light-emitting device 101 of thisembodiment, part of the n-side electrode is made of a high-efficiencyreflection film and the dielectric laminated film 11 having highreflection characteristics is adopted, and thereby, the almost entiresurface of the main surface 1 a of the laminated structure is in whichthe electrodes are formed is allowed to have a reflection structure, andalmost all of the emitted light repeating reflection inside thesemiconductor layer can be reflected to the substrate side. Hence, thelight comes not to be absorbed by the mounting material, and improvementof the light extraction efficiency can be expected. Part of the n-sideelectrode 7 facing the p-side electrode 4 that is a region on which thecurrent relatively concentrates during energization is formed from anelectrode structure having low contact resistance, and thereby, theinfluence on the electrical characteristics exerted by forming ahigh-efficiency reflection film in the n-side electrode 7 can besuppressed to the minimum.

In the semiconductor light-emitting device 101 according to thisembodiment, by using crystal on the single crystal AlN buffer,high-concentration-Si doping can be performed in the n-type GaN contactlayer, and the contact resistance with respect to the first n-sideelectrode film 7 a serving as an ohmic contact region of the n-sideelectrode 7 can be drastically reduced, and current spreading in thefirst n-side electrode film 7 a can be suppressed and the currentconcentrates more on a region near to the p-side electrode, and hence,the n-side electrode 7 can be designed so that the ohmic contact area isdecreased, and the high-efficiency reflection film area is increased,and additionally, high emission efficiency can be realized even in theshorter wavelength region than 400 nm, in which the efficiency normallylowers by reducing the crystal defects.

Moreover, when an amorphous or polycrystalline AlN layer is provided forrelaxing the difference of crystal form on the sapphire substrate, thebuffer layer itself becomes an absorber of the light, and hence, thelight extraction efficiency of the light-emitting device comes to lower.By contrast, on the sapphire substrate 10, through a single crystal AlNbuffer layer with high carbon concentration and a single crystal AlNbuffer layer with high purity, the p-type first semiconductor layer 1,the light-emitting layer 3 and the n-type second semiconductor layer areformed, and thereby, the buffer layer is difficult to become an absorberof the light, and the crystal defects can be drastically reduced, andhence, the absorber in the crystal can be drastically reduced. In thiscase, the emitted light can repeat the reflection many times in thecrystal, and the light extraction efficiency to the horizontal directioncan be enhanced, and the light can be reflected efficiently to thehigh-efficiency reflection region of the n-side electrode 7. By theseeffects, improvement of emission intensity, high through-put, and lowcost can be realized.

FIG. 3 is a schematic plan view showing a modified example of thesemiconductor light-emitting device according to the first embodiment ofthe invention.

As shown in FIG. 3, in a semiconductor light-emitting device 101 a ofthe modified example according to the first embodiment of the invention,the n-side electrode 7 is surrounded by the p-side electrode 4 and hasportions extending to four directions.

In the n-side electrode 7 like this, the portions extending to fourdirections and the portion facing the p-side electrode 4 are formed fromthe first n-side electrode film 7 a serving as an ohmic contact region.Moreover, the central portion of the n-side electrode 7 is formed fromthe second n-side electrode film 7 b having high reflectance.

According to the semiconductor light-emitting device 101 a having such aconfiguration, the ohmic contact is ensured in the portion facing thep-side electrode 4, and the current can be flowed evenly over the entiredevice efficiently, and the region for wire bonding or bump is ensuredin the central portion of the n-side electrode 7, and light can bereflected with high reflectance in this portion.

FIG. 4 is a schematic plan view showing a modified example of thesemiconductor light-emitting device according to the first embodiment ofthe invention.

As shown in FIG. 4, in the semiconductor light-emitting device 101 b ofanother modified example according to the first embodiment of theinvention, the region for wire bonding or bump out of the n-sideelectrode 7 is provided at a corner of the device. The n-side electrode7 has portions extending to four directions so as to cut into the p-sideelectrode 4.

In the n-side electrode 7 having such a configuration, the portionextending in the p-side electrode is formed from the first n-sideelectrode film 7 a, and the corner portion for wire bonding or bump isformed from the second n-side electrode film 7 b.

According to the semiconductor light-emitting device 101 b having such aconfiguration, the current can be evenly flowed efficiently throughoutentire device, and the light emitted from the light-emitting layer canbe reflected with high reflectance at the second n-side electrode film 7b to be taken out.

As shown in FIGS. 1A, 1B, 3, and 4, the n-side electrode region throughwhich the current injected from the outside of the semiconductorlight-emitting device into the p-side electrode 4 and flowing throughthe semiconductor layer to the n-side electrode 7 is taken out to theoutside of the semiconductor light-emitting device has no other choicethan to be designed to be large in order to form wire bonding or bumpfor the contact between the semiconductor light-emitting device and theexternal terminal. However, its entire region is not required to haveohmic characteristics, and most of the region thereof may be the n-sideelectrode 7 having high-efficiency reflection characteristics.

In this case, if the n-side electrode region having ohmiccharacteristics outside this region can be ensured as in thesemiconductor light-emitting device 101 b, the entire region for takingout the light to the outside of the semiconductor light-emitting devicecan be turned into the high-efficiency reflection film.

It is noted that the size of the pad required for bonding in the n-sideelectrode 7 is, for example, approximately 50 μm to 150 μm.

On the other hand, the dielectric laminated film 11 has a higherreflectance and a wider margin with respect to the film thickness or thewavelength as the refractive index ratio of the combined dielectricmaterials is larger or as the number of combinations (number of pairs)of the layers having different refractive indices is larger.

FIGS. 5A and 5B are graphic views illustrating characteristics of thesemiconductor light-emitting device according to the first embodiment ofthe invention.

That is, FIGS. 5A and 5B illustrate simulation results relating to thereflectance of the emitted light incident perpendicularly to thedielectric laminated film 11 from the GaN layer, and FIG. 5A illustratesrefractive index ratio dependency of the reflectance, and FIG. 5Billustrates pair number dependency of the reflectance. The horizontalaxis of FIG. 5A represents the refractive index ratio of two kinds ofcombined dielectric materials in the dielectric laminated film 11, andthe horizontal axis of FIG. 5B represents the number of pairs of twokinds of combined dielectric materials in the dielectric laminated film11, and the vertical axes of FIGS. 5A and 5B represent the reflectance.

In the simulation, using a physical property value of the material ofthe dielectric laminated film 11 of the semiconductor light-emittingdevice 101 described previously, each of the parameters is varied.

As shown in FIGS. 5A and 5B, in each of the conditions of the refractiveindex ratio and the number of the pairs, the reflectance near to 100%can be obtained by appropriately selecting the conditions.

For example, as shown in FIG. 5A, for setting the reflectance to be 95%or more, it is desirable that the refractive index ratio is 1.4 or more.

Moreover, as shown in FIG. 5B, for setting the reflectance to be 95% ormore, it is desirable that the number of the pairs is 3 or more.

As the angle of incident with respect to the dielectric laminated film11 from the GaN layer is more inclined from the verticality, thereflectance increases, and the light is totally reflected at a certainthreshold angle.

Considering these properties, the dielectric laminated film 11functioning as a reflection film having higher performance than a metalreflection film is adopted by selecting the design condition, and henceimprovement of the light extraction efficiency is expected. In thesemiconductor light-emitting device 101 according to this embodiment,the design reflectance of the dielectric laminated film 11 is 99.7° A).

For the dielectric laminated film 11, oxide, nitride, oxynitride or thelike of silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti),niobium (Nb), Tantalum (Ta), magnesium (Mg), hafnium (Hf), cerium (Ce),zinc (Zn), or the like can be used. It is preferable that the total filmthickness of the dielectric films to be laminated is 50 nm or more forensuring insulation and 1000 nm or less for suppressing cracks of thedielectric films. In particular, for suppressing the stress betweenheterogeneous materials due to heating during operating the device, itis preferable that the first layer in the semiconductor layer side ofthe dielectric laminated film 11 is a material having a linear expansioncoefficient near to that of the semiconductor layer. For example, whenthe semiconductor layer is made of GaN, it is preferable that as thefirst layer in the semiconductor layer side of the dielectric laminatedfilm 11, for example, SiN is used.

In the dielectric laminated film 11, laminating different kinds ofdielectric materials enables the stress applied to the inside to berelaxed, and hence, even if the total film thickness increases, damagesuch as break or crack is difficult to be caused in comparison to thecase of a single-layer. Moreover, the stress with respect to thesemiconductor layer can also be relaxed, and hence, the reliability isimproved. In particular, laminating the dielectric materials havingtensile stress and compressive stress promotes the stress-relaxingeffect.

As described above, in the semiconductor light-emitting device 101according to this embodiment, part of the n-side electrode 7 is formedfrom the second n-side electrode film 7 b having high reflectance, andfurthermore, the dielectric laminated film 11 having high reflectioncharacteristics is adopted, and thereby, the almost entire surface ofthe main surface 1 a of the semiconductor layer in which the electrodesare formed is allowed to have a reflection structure. Thereby, inperforming flip chip mount, almost all of the emitted light repeatingthe reflection inside the semiconductor layer can be reflected to thesubstrate side, and hence, the light comes not to be absorbed by themounting material, and improvement of light extraction efficiency can beexpected.

The semiconductor light-emitting device 101 according to this embodimentis made of the semiconductor layer including at least the n-typesemiconductor layer, the p-type semiconductor layer, and thelight-emitting layer sandwiched between them, and the material of thesemiconductor layer is not particularly limited, but gallium nitridecompound semiconductor such as Al_(x)Ga_(1-x-y)In_(y)N (x≧0, y≧0, x+y≦0)is used. The method for forming these semiconductor layers is notparticularly limited, but techniques such as metal organic chemicalvapor deposition and molecular beam epitaxial growth can be used.

Moreover, in the semiconductor light-emitting device according to thisembodiment, the substrate material is not particularly limited, but ageneral substrate such as sapphire, SiC, GaN, GaAs, Si can be used. Thesubstrate may be finally removed.

Second Embodiment

FIG. 6 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to asecond embodiment of the invention.

As shown in FIG. 6, in the semiconductor light-emitting device 102according to the second embodiment of the invention, an n-side pad(first pad) 75 is provided on the n-side electrode 7, and the p-sideelectrode 4 has a second p-side electrode film (fourth metal film) 4 bprovided on the p-side semiconductor 2 and serving as a high-efficiencyreflection film, and a first p-side electrode film (third metal film) 4a provided on the second p-side electrode film 4 b and being made of ametal not necessarily requiring the high-efficiency reflectioncharacteristics. The other configurations can be the same as thesemiconductor light-emitting device 101 illustrated in FIGS. 1A and 1B,and hence, the description thereof will be omitted.

That is, the p-side electrode 4 has the first p-side electrode film 4 aand the second p-side electrode film 4 b provided between the firstp-side electrode film 4 a and the second semiconductor layer 2 andhaving a higher reflectance for the light emitted from thelight-emitting layer 3 than the first p-side electrode film 4 a.

As described above, in the semiconductor light-emitting device 102according to this embodiment, the n-side pad 75 is provided on then-side electrode 7, and hence, the electrode area required for bondingor bump formation can be obtained, and the electrical characteristicsbecome stable. Furthermore, the natural oxidation of the second n-sideelectrode film 7 b can be prevented, and life of the device is improved.

Because the second p-side electrode film 4 b that is a high-efficiencyreflection film is provided on the side of the p-type semiconductorlayer 2 of the p-side electrode 4, the reflectance is further improved.And, on the second p-side electrode film 4 b, the first p-side electrodefilm 4 a that does not require the high efficiency reflectioncharacteristics and can prevent the second p-side electrode film 4 bfrom being oxidized or sulfurated by blocking the second p-sideelectrode film 4 b from the outside air, and thereby, high reliabilitycan be obtained.

The second p-side electrode film 4 b can include at least any one ofsilver, aluminum, and an alloy containing any one thereof. That is, thesecond p-side electrode film 4 b may be a single-layer of silver oraluminum, or may be an alloy layer containing silver or aluminum and ametal other than them.

The second p-side electrode film 4 b can be made of the same material asthe second n-side electrode film 7 b.

Moreover, the first p-side electrode film 4 a is made of a metal notcontaining silver and aluminum and is in electrical contact with thesecond p-side electrode film 4 b. The material of the first p-sideelectrode film 4 a is not particularly limited, but may be asingle-layer film or multilayer film of metal, an alloy layer of metal,a single-layer film or multilayer film of conductive oxide film, or acombination thereof. The film thickness of the first p-side electrodefilm 4 a is not particularly limited, but can be selected in the rangeof, for example, 100 nm to 1000 nm.

The reflection efficiency of a normal single-layer metal film for thevisible light band has tendency of lowering in the ultraviolet band of400 nm or less as the wavelength becomes shorter, however silver andaluminum have high reflection efficiency characteristics also for thelight in the ultraviolet band of 370 nm or more 400 nm or less.Therefore, when the second p-side electrode film 4 b is made of an alloyof silver or aluminum in the semiconductor light-emitting device of theultraviolet emission, it is preferable that the second p-side electrodefilm 4 b on the semiconductor interface side has a larger componentratio of at least any one of silver and aluminum. It is preferable thatthe film thickness of the second p-side electrode film 4 b is 100 nm ormore for ensuring the reflection efficiency for light.

When at least any one of silver, aluminum, and an alloy containing anyone thereof is used for the second p-side electrode film 4 b, as thedistance between the second p-side electrode film 4 b and the n-sideelectrode 7 increases, the risks of insulation fault and breakdownvoltage failure due to migration of silver or aluminum, or the alloy ofany one thereof are reduced. When the p-side electrode 4 facing then-side electrode 7 in the vicinity of the center of the device is formedto the end of the p-type contact layer as far as the process conditionsuch as exposure accuracy allows, the light extraction efficiencyincreases. With regard to the current path from the second p-sideelectrode film 4 b to the first n-side electrode film 7 a of the n-sideelectrode 7, the current tends to concentrate on the region with theshortest distance between the second p-side electrode film 4 b and thefirst n-side electrode film 7 a, and hence, for relaxing the electricfield concentration, it is preferable that the region with the aboveshortest distance out of the region in which the second p-side electrodefilm 4 b faces the first n-side electrode film 7 a is designed to be aslong as possible.

Moreover, in plan view, as the length of the region in which the secondp-side electrode film 4 b faces the first n-side electrode film 7 abecomes larger, the number of current paths from the second p-sideelectrode film 4 b to the first n-side electrode film 7 a increases, andhence, the electric field concentration is relaxed, and the degradationof the second p-side electrode film 4 b is suppressed. By consideringthese effects, the area and shape of the second p-side electrode film 4b and the distance between the second p-side electrode film 4 b and thefirst n-side electrode film 7 a can be appropriately determined.

On the other hand, it is preferable that the pad of the n-side electrode7 covers the entirety of the second n-side electrode film 7 b to blockthe second n-side electrode film 7 b from the outside air. Moreover, atleast part of the pad is in electrical contact with the first n-sideelectrode film 7 a. The film thickness of the pad is not particularlylimited, but can be selected in the range of, for example, 100 nm to5000 nm. Forming the n-side pad 75 provides an electrode area requiredfor bonding or bump formation and additionally, can prevent naturaloxidation of the second p-side electrode film 7 b to improve the devicelifetime.

Next, one example of a method for forming the n-side electrode 7, thep-side electrode 4, and the dielectric laminated film 11 on thesemiconductor layer in the semiconductor light-emitting device 102according to this embodiment will be described.

FIGS. 7A to 7C are schematic cross-sectional views by step sequenceillustrating the process for manufacturing the semiconductorlight-emitting device according to the second embodiment of theinvention.

FIGS. 8A to 8C are schematic cross-sectional views by step sequencefollowing FIGS. 7A to 7C.

First, as shown in FIG. 7A, in part of the region of the p-typesemiconductor layer 2, until the above n-type contact layer is exposed,the p-type semiconductor layer 2 and the light-emitting layer 3 areremoved by dry etching using a mask.

Next, as shown in FIG. 7B, the n-side electrode region having ohmiccharacteristics, namely the first n-side electrode film 7 a is formed.That is, a patterned lift-off resist, which is not shown, is formed onthe exposed n-type contact layer, and using, for example, a vacuumdeposition apparatus, the first n-side electrode film 7 a made of, forexample, Ti/Al/Ni/Au serving as the ohmic contact region is formed witha film thickness of 500 nm, and sintered in a nitrogen atmosphere at550° C.

Next, as shown in FIG. 7C, to form the p-side electrode 4, a patternedlift-off resist is formed on the p-type contact layer, and using, forexample, a vacuum deposition apparatus, the film serving as the secondp-side electrode film 4 b made of Ag, for example, is formed with a filmthickness of 200 nm, and sintered in a nitrogen atmosphere at 350° C.after the lift off.

Subsequently, as shown in FIG. 8A, the n-side electrode region havinghigh-efficiency reflection characteristics is formed. That is, alift-off resist is formed with an opening on a region on the n-typecontact layer located on the opposite side of the p-side electrode 4across the first n-side electrode film 7 a that is an n-side electroderegion having ohmic characteristics (not shown).

Here, considering the alignment accuracy of the pattern, part of thefirst n-side electrode film 7 a that is an n-side electrode having ohmiccharacteristics in the side facing the p-side electrode 4 may be opened.

Conversely, in order that the n-side electrode having high efficiencyreflection characteristics, namely, the second n-side electrode film 7 bdoes not climb up the n-side electrode having ohmic characteristics,namely, the first n-side electrode film 7 a, the both electrodes may bedesigned with a slight spacing therebetween in considering the alignmentaccuracy of the pattern.

Also, the n-side electrode having high efficiency reflectioncharacteristics, namely, the second n-side electrode film 7 b may bedesigned so as to cover the part or the entirety of the n-side electrodehaving ohmic characteristics, namely, the first n-side electrode film 7a.

And, a vacuum deposition apparatus is used to form, for example, thelaminated layer of Al (thickness of approximately 0.2 to 0.5 μm)/Ni(thickness of approximately 10 to 50 μm)/Au (thickness of approximately0.05 to 1 μm), and then the lift off is performed to form the secondn-side electrode film 7 b serving as a high-efficiency reflection film.In the laminated film, Al layer serves as the high-efficiency reflectionfilm. Moreover, Au serves to protect the high-efficiency reflection filmfrom degradation by natural oxidation or chemical treatment or the likeduring the device fabrication process. And, for adhesiveness improvementand alloying prevention of Al and Au, Ni is sandwiched between them.

Next, as shown in FIG. 8B, a patterned lift-off resist, which is notshown, is formed on the semiconductor layer, and the first p-sideelectrode film 4 a illustratively made of a laminated film of Pt/Au isformed with a film thickness of 500 nm on the region provided with Ag toform the p-side electrode 4.

Furthermore, as shown in FIG. 8C, similarly, a patterned lift-offresist, which is not shown, is formed likewise on the semiconductorlayer, and a laminated film of, for example, Ti/Pt/Au is formed with athickness of 500 nm so as to cover the second n-side electrode film ofthe n-side electrode 7 having high-efficiency reflection characteristicsand the first n-side electrode film 7 a of the n-side electrode 7 havingohmic characteristics to form the n-side pad 75.

A vacuum deposition apparatus is used to form, for example, five groupsof the combinations of the laminated film of SiO₂ and TiO₂, namely, thelaminated film composed of ten dielectric layers in total on thesemiconductor layer. The thickness of each of the SiO₂ film and the TiO₂film is set to be λ/(4n) in which n is a refractive index of each of thedielectric layers and λ is an emission wavelength from thelight-emitting layer 3.

Furthermore, thereon, a patterned resist, which is not shown, is formed,and ammonium fluoride treatment removes the dielectric laminated film sothat the p-side electrode 4 and the n-side electrode 7 are exposed toform the dielectric laminated film 11 illustrated in FIG. 6.

Next, this is cut by cleavage or diamond blade or the like to be adiscrete LED device, and thereby, the semiconductor light-emittingdevice 102 according to this embodiment is fabricated.

In the semiconductor light-emitting devices 101, 102 according to thefirst and second embodiments, as the area of the first n-side electrodefilm 7 a having ohmic characteristics composing the n-side electrode 7is larger, the operation voltage tends to decrease, because the ohmiccontact region increases. However, because the current path duringoperation tends to concentrate on the n-side electrode facing the p-sideelectrode 4, namely, on the first n-side electrode film 7 a, if the areaof the first n-side electrode film 7 a is increased to a certain extent,the decreasing rate is saturated.

On the other hand, as the area of the first n-side electrode film 7 ahaving ohmic characteristics composing the n-side electrode 7 issmaller, the n-side electrode having high-efficiency reflectioncharacteristics, namely, the second n-side electrode film 7 b can bedesigned to have a large area, and hence, the light extractionefficiency is expected to increase.

Moreover, as the area of the first n-side electrode film 7 a having anohmic characteristic is smaller, the probability that the lightreflected in the semiconductor light-emitting device is absorbeddecreases, and hence, the light extraction efficiency is expected toincrease.

Considering these, the area ratio and shape of the first n-sideelectrode film 7 a of the n-side electrode having ohmic characteristicsand the second n-side electrode 7 b of the n-side electrode havinghigh-efficiency reflection characteristics can be appropriatelydetermined.

That is, in the semiconductor light-emitting device 102 according tothis embodiment, the portion of the n-side electrode 7 facing the secondp-side electrode film 4 b of the p-side electrode 4 on which the currentis relatively concentrated during energization is formed from the firstn-side electrode film having low contact resistance, and thereby,influence on electrical characteristics exerted by forming thehigh-efficiency reflective film that does not necessarily have lowcontact resistance in the n-side electrode 7 can be suppressed to theminimum.

With regard to the current path from the second p-side electrode film 4b to the first n-side electrode film 7 a of the n-side electrode 7, thecurrent tends to concentrate on the region with the shortest distancebetween the second p-side electrode film 4 b and the first n-sideelectrode film 7 a, and hence, for relaxing the electric fieldconcentration, it is preferable that the region with the above shortestdistance out of the region in which the second p-side electrode film 4 bfaces the first n-side electrode film 7 a is designed to be as long aspossible.

Moreover, in plan view, as the length of the region in which the secondp-side electrode film 4 b faces the first n-side electrode film 7 abecomes larger, the number of current paths from the second p-sideelectrode film 4 b to the first n-side electrode film 7 a increases, andhence, the electric field concentration is relaxed, and the degradationof the second p-side electrode film 4 b is suppressed. By consideringthese effects, the area and shape of the second n-side electrode film 7b and the first n-side electrode film 7 a and the area and shape of theentire n-side electrode 7 can be freely determined.

Third Embodiment

FIG. 9 is a schematic cross-sectional view illustrating theconfiguration of the semiconductor light-emitting device according to athird embodiment of the invention.

As shown in FIG. 9, in the semiconductor light-emitting device 103 aaccording to the third embodiment of the invention, an n-sidetransparent electrode (transparent electrode) 7 t is provided betweenthe n-type electrode layer 1 and the second n-side electrode 7 b. Otherthan this, this semiconductor light-emitting device can be the same asthe semiconductor light-emitting devices according to the first andsecond embodiments, and hence, the description will be omitted. In thisfigure, the substrate 10 illustrated in FIG. 1, the laminated structure1 s and the p-side electrode 4 are omitted.

The n-side transparent electrode 7 t contains at least one of nickel,indium tin oxide, and zinc oxide, and is in electrical contact with then-type contact layer and the second n-side electrode film 7 b. Thetransparent electrode refers to a material having a larger band gap thanthe transmitted emission wavelength or a metal film having a filmthickness that is sufficiently smaller than the inverse number of theabsorption coefficient at the transmitted emission wavelength.

The n-side transparent electrode 7 t plays a role of transmitting thelight from the light-emitting layer 3 that is reflected in thesemiconductor light-emitting device and reflecting the light at thesecond n-side electrode 7 b, a role of having contact with the n-typesemiconductor layer 1 with good electrical characteristics, and a roleof preventing silver or aluminum used in the first n-side electrode film7 a from reacting with the n-type semiconductor layer 1 or fromdiffusing into the n-type semiconductor layer 1, and hence, it ispreferable that the n-side transparent electrode 7 t has substantiallythe same shape as the second n-side electrode film 7 b. The filmthickness of the n-side transparent 7 t is not particularly limited, butcan be selected in the range of, for example, 1 nm to 500 nm.

The semiconductor light-emitting device 103 a according to thisembodiment having such a configuration can satisfy both of thereflection characteristic and the electrical characteristics byproviding the transparent electrode in the n-side electrode 7 and highreliability can be obtained.

FIG. 10 is a schematic cross-sectional view illustrating theconfiguration of another semiconductor light-emitting device accordingto the third embodiment of the invention.

As shown in FIG. 10, in another semiconductor light-emitting device 103b according to the third embodiment of the invention, between the p-sidesemiconductor layer 2 and the p-side electrode 4, a p-side transparentelectrode (transparent electrode) 4 t is provided. Other than this, thissemiconductor light-emitting device can be the same as the semiconductorlight-emitting device according to the first and second embodiments, andhence, the description thereof will be omitted. In the figure, thesubstrate 10 and n-side electrode 7 illustrated in FIG. 1A are omitted.

The specific example illustrated in FIG. 10 is the case that the p-sideelectrode 4 has the second p-side electrode layer 4 b, and in this case,between the p-type semiconductor layer 2 and the second p-side electrodefilm 4 b, the p-side transparent electrode 4 t is provided.

Moreover, in the specific example illustrated in FIG. 10, the p-sidetransparent electrode 4 t is provided over the entire surface of thep-side electrode 4 (second p-side electrode film 4 b), but the inventionis not limited thereto, but between at least part of the p-sideelectrode 4 (second p-side electrode film 4 b) and the p-typesemiconductor layer 2, the p-side transparent electrode 4 t can beprovided.

The p-side transparent electrode 4 t contains at least one of nickel,indium tin oxide, and zinc oxide, and is in electrical contact with thep-type contact layer and the p-side electrode 4 (the second p-sideelectrode film 4 b).

The p-side transparent electrode 4 t plays a role of transmitting thelight from the light-emitting layer 3 and reflecting the light at thep-side electrode 4 (second p-side electrode film 4 b), a role of havingcontact with the p-type semiconductor layer 2 with good electriccharacteristics, and a role of preventing silver or aluminum used in thesecond p-side electrode film 4 b from reacting with the p-typesemiconductor layer 2 or from diffusing into the p-type semiconductorlayer 2, and hence, it is preferable that the p-side transparentelectrode 4 t has substantially the same shape as the p-side electrode 4(second p-side electrode film 4 b). The film thickness of the p-sidetransparent electrode 4 t is not particularly limited, but can beselected in the range of, for example, 1 nm to 500 nm.

The semiconductor light-emitting device 103 b according to thisembodiment having such a configuration can satisfy both of thereflection characteristic and the electric characteristics by providingthe transparent electrode in the p-side electrode 4 and high reliabilitycan be obtained.

In the semiconductor light-emitting device according to this embodiment,the transparent electrodes may be provided in both of the n-sideelectrode 7 and the p-side electrode 4. Thereby, the semiconductorlight-emitting device having higher light output, more stable electriccharacteristics and higher reliability can be realized.

That is, the semiconductor light-emitting device according to thisembodiment can further comprise the transparent electrode(s) provided inat least part of at least any one between the n-type semiconductor layerand the n-side electrode 7 and between the p-type semiconductor layer 2and the p-side electrode 4.

In any one of the semiconductor light-emitting devices 101, 101 a, 101b, and 102 described previously, the transparent electrode(s) (at leastany one of the n-side transparent electrode 7 t and the p-sidetransparent electrode 4 t) can be provided.

Fourth Embodiment

FIG. 11 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to afourth embodiment of the invention.

As shown in FIG. 11, in the semiconductor light-emitting device 104according to the fourth embodiment of the invention, the semiconductorlayers sandwiching the light-emitting layer 3, namely, the laminatedstructure 1 s has a taper-shaped portion 1 t that is a gradient, andtherewith, the dielectric laminated film 11 obliquely coats thetaper-shaped portion 1 t. That is, the laminated structure 1 s has theinclined taper-shaped portion 1 t with respect to the layer surface ofthe first and second semiconductor layers 1 and 2.

Other than this, the semiconductor light-emitting device 104 can be thesame as the semiconductor light-emitting device 101 according to thefirst embodiment, and hence, the description thereof will be omitted.

In the laminated structure 1 s composed of the n-type semiconductorlayer 1, the light-emitting layer 3 and the p-type semiconductor layer2, to provide the n-side electrode 7 and the p-side electrode 4 on thesame side of the main surface 1 a, a step is provided between the p-typesemiconductor layer 2 and the light-emitting layer 3 and the n-typesemiconductor layer 1.

In this case, the dielectric laminated film 11 is also provided on thisstep portion, however the thickness of the dielectric laminated film 11becomes small on this step portion, and thereby, the reflectioncharacteristics of the dielectric laminated film 11 is affected.

In this case, in the semiconductor light-emitting device 104 accordingto this embodiment, by forming the step portion with a tapered shape,this influence is suppressed to the extent possible and the highreflectance can be maintained.

That is, the emitted light incident to the cross section of thesemiconductor layer sandwiching the light-emitting layer 3 is affectedby the film thickness of the dielectric laminated film 11 formed in thevertical direction to the cross section of the semiconductor layer, andhence, becomes affected by the dielectric laminated film 11 displaced tothe direction in which the film is thinner than the designed filmthickness thereof in the above step portion.

In this case, by forming the step portion with a tapered shape, theinfluence is suppressed and high reflectance can be maintained. As theangle of the taper is smaller, that is, the slope of the taper-shapedportion 1 t is looser, the dielectric laminated film in thesemiconductor layer section functions as designed.

FIG. 12 is a graphic view illustrating the characteristics of thesemiconductor light-emitting device according to the fourth embodimentof the invention.

That is, FIG. 12 illustrates a calculation result of the relationbetween the angle of the taper and the reflectance of the dielectriclaminated film 11, and the horizontal axis represents the angle of thetaper and the vertical axis represents the reflectance of the dielectriclaminated film 11. Here, the angle of the taper is an angle made by themain surface 1 a of the laminated structure 1 s and the surface of thetaper-shaped portion 1 t, and as the angle of the taper is smaller, thegradient of the slope of the taper-shaped portion 1 t becomes loose, andwhen the angle of the taper is 90°, the step portion of the n-typesemiconductor layer 1 and the p-type semiconductor layer 2 has astair-like side surface. And, FIG. 12 illustrates the calculation resultin which the design condition described in the semiconductorlight-emitting device 101 according to the first embodiment is used.

As shown in FIG. 12, when the angle of the taper is approximately 40° orless, the high reflection characteristic is shown, but when the angle ofthe taper is larger than 40°, the high reflection characteristic asdesigned comes not to be shown, because the film thickness of thedielectric laminated film 11 is too small.

The margin of the high reflection characteristic with respect to theangle of this taper becomes wide with increasing refractive index ratioof the two kinds of dielectric materials to be laminated.

Moreover, providing the taper-shaped portion 1 t can prevent thedielectric laminated film 11 from being disconnected by the step in thecross section of the semiconductor layer sandwiching the light-emittinglayer 3.

The angle of the taper of the taper-shaped portion 1 t can beappropriately determined based on the device area, emissioncharacteristics, processing accuracy, or the like of the semiconductorlight-emitting device.

Fifth Embodiment

FIG. 13 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to afifth embodiment of the invention.

FIGS. 14A to 14C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the fifth embodiment of the invention.

FIGS. 15A to 15C are schematic cross-sectional views by step sequencefollowing FIGS. 14A to 14C.

FIG. 16 is a schematic cross-sectional view by step sequence followingFIGS. 15A to 15C.

As shown in FIG. 13, in the semiconductor light-emitting device 105according to the fifth embodiment of the invention, the first p-sideelectrode film 4 a is in contact with the p-type semiconductor layer 2(p-type contact layer) being not covered with the second p-sideelectrode film 4 b, and a dielectric film 11 a is provided on the regionof the p-type contact layer other than the region being in contact withthese electrodes. The first p-side electrode film 4 a is provided tocover the second p-side electrode film 4 b and to be in contact withpart of the dielectric film 11 a. The dielectric laminated film 11described previously is provided so as to cover the dielectric film 11 aand to expose part of the first p-side electrode film 4 a, the firstn-side electrode film 7 a and the second n-side electrode film 7 b.

That is, the semiconductor light-emitting device 105 further comprisesthe dielectric film 11 a provided between the dielectric laminated film11 and at least part of the n-side semiconductor layer 1 and the p-sidesemiconductor layer 2 being not covered with the n-side electrode 7 andthe p-side electrode 4.

The dielectric film 11 a has a projecting portion, and on the projectingportion, part of at least any one of the n-side electrode 7 and thep-side electrode 4 is provided. In this specific example, on theprojecting portion, the first p-side electrode film 4 a that is part ofthe p-side electrode 4 is provided, and the projecting portion is coatedwith the first p-side electrode film 4 a.

Other than this, the semiconductor light-emitting device 105 can be thesame as the semiconductor light-emitting device 102 according to thesecond embodiment, and the description thereof will be omitted.

In the semiconductor light-emitting device 105 according to thisembodiment, the first p-side electrode film 4 a coats the second p-sideelectrode film 4 b, the p-type contact layer exposed between the secondp-side electrode film 4 b and the dielectric film 11 a, and part of thedielectric film 11 a.

Thereby, the second p-side electrode film 4 b is coated with the firstp-side electrode film 4 a, and, is isolated from the outside air or thedielectric film 11 a, and hence, is difficult to be exposed to moistureor ion impurities. As a result, migration, oxidation and sulfurationreaction of the second p-side electrode film 4 b can be suppressed.

Moreover, the first p-side electrode film 4 a is formed immediatelybeside the end of the second p-side electrode film 4 b on the sidefacing the n-side electrode 7, and the current path is formedimmediately beside the second p-side electrode film 4 b, and hence, thecurrent concentration on the second p-side electrode film 4 b isrelaxed.

At the same time, in the vicinity of the end of the dielectric film 11 afacing the end of the second p-side electrode film 4 b, the regionsandwiched between the p-type semiconductor layer 2 and the first p-sideelectrode film 4 a is formed, and hence, a weak electric field isapplied between the p-type semiconductor layer 2 and the first p-sideelectrode film 4 a across the dielectric film 11 a. As a result, thestructure in which the electric field becomes gradually weak from thesecond p-side electrode film 4 b to the dielectric film 11 a can beformed, and hence, the electric field concentration in this region canbe relaxed.

Furthermore, particular ingenuity is not required for the manufacturingprocess, and the semiconductor light-emitting device can be formed bythe same processes and the same number of the processes as conventionalones. By these effects, reduction of leak current of the semiconductorlight-emitting device, improvement of insulating characteristics,improvement of breakdown voltage characteristics, improvement ofemission intensity, enlargement of the life, high through-put, and lowcost can be realized.

It is preferable that the electric characteristics between the firstp-side electrode film 4 a and the p-type contact layer serving as theuppermost layer of the p-type semiconductor layer 2 have worse ohmiccharacteristics than those between the second p-side electrode film 4 band the p-type contact layer, and the contact resistance is larger.Thereby, the current can be efficiently injected into the light-emittinglayer 3 located immediately below the second p-side electrode film 4 b,and the light emitted from immediately below the second p-side electrodefilm 4 b can be reflected to the substrate side with high efficiency,and hence, the light extraction efficiency can be improved.

As described previously, the first p-side electrode film 4 a coats thesecond p-side electrode film 4 b, the p-type contact layer exposedbetween the second p-side electrode film 4 b and the dielectric film 11a, and part of the dielectric film 11 a, and in particular, it ispreferable that the entire region of the dielectric film 11 a on theside facing the n-side electrode 7 is coated.

And, it is preferable that the length that the first p-side electrodefilm 4 a coats the dielectric film 11 a is in the range of 0.5 μm to 10μm in consideration of the pattern alignment accuracy on themanufacturing process and the area securement of the second p-sideelectrode film 4 b functioning as the reflection film.

Hereinafter, a specific example of the method for producing thesemiconductor light-emitting device 105 according to this embodimentwill be described. First, as shown in FIG. 14A, in the region of part ofthe p-type semiconductor layer 2, until the n-type contact layer isexposed to the surface, the p-type semiconductor layer 2 and thelight-emitting layer 3 are removed by dry etching using a mask.

Next, as shown in FIG. 14B, using a thermal CVD apparatus, SiO₂ filmserving as the dielectric film 11 a is formed on the semiconductor witha film thickness of 100 nm.

Next, as shown in FIG. 14C, the n-side electrode region having ohmiccharacteristics, namely, the first n-side electrode film 7 a is formed.That is, a patterned lift-off resist, which is not shown, is formed onthe semiconductor layer, and part of the SiO₂ film on the exposed n-typecontact layer, is removed by ammonium fluoride treatment. In the regionin which the SiO₂ film is removed, using a vacuum deposition apparatus,the first n-side electrode film 7 a made of, for example, Ti/Al/Ni/Auserving as the ohmic contact region is formed with a film thickness of500 nm, and sintered in a nitrogen atmosphere at 550° C.

Subsequently, to form the p-side electrode 4, a patterned lift-offresist, which is not shown, is formed on the semiconductor layer, andpart of the SiO₂ film on the p-type contact layer is removed by ammoniumfluoride treatment.

In this case, the treatment time of the ammonium fluoride is adjusted sothat the p-type contact layer is exposed between Ag film of the secondp-side electrode film 4 b to be described later and the SiO₂ film of thedielectric film 11 a. In one specific example, in the case where theetching rate is 400 nm/min, the total of the time for removing the SiO₂film of the region in which Ag film is formed and the time ofoveretching for exposing the p-type contact layer located immediatelybeside the above region by a width of 1 μm is approximately 3 minutes.

In the region where the SiO₂ film is removed, using a vacuum depositionapparatus, as the second p-side electrode film 4 b, for example, a Aglayer is formed with a film thickness of 200 nm, and sintered in anitrogen atmosphere at 350° C. after the lift-off.

Next, as shown in FIG. 15A, the n-side electrode region havinghigh-efficiency reflection characteristics is formed. That is, alift-off resist is formed with an opening on the region of the n-typecontact layer opposite to the p-side electrode 4 of the first n-sideelectrode film 7 a that is the n-side electrode region having ohmiccharacteristics. Part of the SiO₂ film on the n-type contact layer isremoved by the ammonium fluoride treatment, and using a vacuumdeposition apparatus, for example, a film made of Al/Ni/Au is formed,and then, the lift-off is performed, and thereby, the second n-sideelectrode film 7 b serving as a high-efficiency reflection film isformed.

Next, as shown in FIG. 15B, a patterned lift-off resist, which is notshown, is formed on the semiconductor layer, and the first p-sideelectrode film 4 a made of, for example, Pt/Au is formed with a filmthickness of 500 nm so as to coat the entire region provided with Ag isformed, the entire region of the p-type contact layer exposed to thesurface that exists immediately beside the Ag region, and part of theSiO₂ film of the dielectric film 11 a. Thereby, the p-side electrode 4is formed.

Furthermore, as shown in FIG. 15C, a patterned lift-off resist, which isnot shown, is formed likewise on the semiconductor layer, a layer madeof, for example, Ti/Pt/Au is formed with a thickness of 500 nm so as tocoat the second n-side electrode film 7 b of the n-side electrode 7having high-efficiency reflection characteristics and the first n-sideelectrode film 7 a of the n-side electrode 7 having ohmiccharacteristics, and thereby, the n-side pad 75 is formed.

And, as shown in FIG. 16, using a vacuum deposition apparatus, the totalof ten layers of five pairs of combinations of SiO₂ and TiO₂ serving asthe dielectric laminated film 11 are formed on the semiconductor. Thethickness of each of the films is represented to be λ/(4n) in which n isa refractive index of each of the dielectric layers and λ is an emissionwavelength from the light-emitting layer 3. Thereon, a patterned resistis formed, and the dielectric material is removed by ammonium fluoridetreatment so that the p-side electrode 4 and the n-side electrode 7 areexposed, and thereby, the dielectric laminated film 11 is formed. Thedielectric laminated film 11 may be formed by a lift-off method so thatthe p-side electrode 4 and the n-side electrode 7 are exposed.

As described above, the semiconductor light-emitting device 105according to this embodiment can be fabricated.

The semiconductor light-emitting device 105 according to this embodimenthas a configuration in which the dielectric film 11 a can be formed onthe semiconductor layer before forming the first n-side electrode film 7a and the second p-side electrode film 4 b, and hence, contaminationattaching to the interface of the electrode and the semiconductor layercan be drastically reduced during the electrode-forming process, andthus, reliability, yield, electrical characteristics, or opticalcharacteristics can be improved.

In the semiconductor light-emitting device 105, it is preferable thatfor the side portion being in contact with the p-type contact layer ofthe first p-side electrode film 4 a, platinum (Pt) or rhodium (Rh)having high environment resistance and relatively high reflectance isused so that the side portion functions as the protective film of thesecond p-side electrode film 4 b or the reflection film with respect tothe emitted light.

When the length that the first p-side electrode film 4 a coats thedielectric film 11 a is large, this is advantageous on obtaining therelaxation structure of the electric field through the dielectric film11 a, but the risk of short-circuiting with the n-side electrode 7becomes high. On the other hand, when the length is short, the risk ofshort-circuiting with n-side electrode 7 becomes low.

There is little influence on the reflectance of the dielectric laminatedfilm 11 by the dielectric film 11 a, and if a plurality of pairs ofdielectric materials having different refractive indices are laminatedin the dielectric laminated film 11, the designed reflectance can besufficiently increased. In the semiconductor light-emitting device 105according to this embodiment, the designed reflectance of the regionwith the dielectric film 11 a and the dielectric laminated film 11superposed is, for example, 99.5%.

The second n-side electrode film 7 b may be formed on the dielectricfilm 11 a without removing the SiO₂ film.

Sixth Embodiment

FIG. 17 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to asixth embodiment of the invention.

FIGS. 18A to 18C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the sixth embodiment of the invention.

FIGS. 19A to 19C are schematic cross-sectional views by step sequencefollowing FIGS. 18A to 18C.

As shown in FIG. 17, the configuration of the semiconductorlight-emitting device 106 according to the sixth embodiment of theinvention has the same as the configuration of the semiconductorlight-emitting device 102 according to the second embodiment. However,in the semiconductor light-emitting device 106 according to thisembodiment, the second p-side electrode film 4 b is composed of the samematerial as the second n-side electrode film 7 b.

In this case, the second p-side electrode film 4 b havinghigh-efficiency reflection characteristics of the p-side electrode 4 andthe second n-side electrode film 7 b having high-efficiency reflectioncharacteristics can be formed simultaneously.

Hereinafter, the method for manufacturing the semiconductorlight-emitting device 106 according to this embodiment will bedescribed.

First, as shown in FIG. 18A, in the region of part of the p-typesemiconductor layer 2, until the n-type contact layer is exposed to thesurface, the p-type semiconductor layer 2 and the light-emitting layer 3are removed by dry etching using a mask.

Next, as shown in FIG. 18B, to form the first n-side electrode film 7 aof the n-side electrode region having ohmic characteristics, a patternedlift-off resist, which is not shown, is formed on the semiconductorlayer. And, on the n-type contact layer, the first n-side electrode film7 a made of, for example, Ti/Al/Ni/Au is formed with a film thickness of500 nm, and sintered in a nitrogen atmosphere at 550° C.

Subsequently, the p-side electrode 4 and the n-side electrode regionhaving high-efficiency reflection characteristics are formedsimultaneously.

That is, a lift-off resist is formed with an opening on the region ofthe n-type contact layer opposite to the p-type contact layer withrespect to the first n-side electrode film 7 a that is an n-sideelectrode region having ohmic characteristics and part of the p-typecontact layer.

Here, considering the alignment accuracy of the pattern, part of then-side electrode (first n-side electrode film 7 a) having ohmiccharacteristics in the side facing the p-side electrode 4 may be opened.

Conversely, in order that the n-side electrode (second n-side electrodefilm 7 b) having high efficiency reflection characteristics does notclimb up the n-side electrode (first n-side electrode film 7 a) havingohmic characteristics, the both electrodes may be designed with a slightspacing therebetween in considering the alignment accuracy of thepattern.

Furthermore, the n-side electrode (second n-side electrode film 7 b)having high-efficiency reflection characteristics may be designed so asto cover the part or the entirety of the n-side electrode (first n-sideelectrode film 7 a) having ohmic characteristics.

As shown in FIG. 18C, using a vacuum deposition apparatus, the secondp-side electrode film 4 b and the second n-side electrode film 7 b madeof, for example, Ag are formed with a thickness of 200 nmsimultaneously, and sintered in a nitrogen atmosphere at 350° C.

Furthermore, as shown in FIG. 19A, a patterned lift-off resist is formedlikewise on the semiconductor layer, and on the region where the secondp-side electrode film 4 b made of Ag is formed, the p-side electrode 4illustratively made of Pt/Au is formed with a film thickness of 500 nm.

Next, as shown in FIG. 19B, a patterned lift-off resist is formedlikewise on the semiconductor layer, and the n-side pad 75illustratively made of Ti/Pt/Au is formed with a thickness of 500 nm soas to coat the second n-side electrode film 7 b having high-efficiencyreflection characteristics and part of the first n-side electrode film 7a having ohmic characteristics.

As shown in FIG. 19C, using a vacuum deposition apparatus, the total often layers of five pairs of combinations of SiO₂ and TiO₂ are formed onthe semiconductor. The thickness of each of the films is represented byλ/(4n) in which n is a refractive index of each of the dielectric layersand is an emission wavelength from the light-emitting layer 3. Thereon,a patterned resist, which is not shown, is formed, and the dielectricmaterial is removed by ammonium fluoride treatment so that the p-sideelectrode 4 and the n-side electrode 7 are exposed, and thereby, thedielectric laminated film 11 is formed. The dielectric laminated film 11may be formed by a lift-off method so that the p-side electrode 4 andthe n-side electrode 7 are exposed.

As described above, the semiconductor light-emitting device 106according to this embodiment can be fabricated.

In the semiconductor light-emitting device 106 according to thisembodiment, the second p-side electrode film 4 b having high-efficiencyreflection characteristics of the p-side electrode 4 and the secondn-side electrode film 7 b having high-efficiency reflectioncharacteristics are composed of the same material, and can be formedsimultaneously.

Thereby, the number of processes can be reduced, and the light generatedin the light-emitting layer can be taken out to the outside efficiently,and hence the semiconductor light-emitting device with high through-putand low cost and the manufacturing method thereof can be provided.

Seventh Embodiment

FIG. 20 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aseventh embodiment of the invention.

FIGS. 21A to 21C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the seventh embodiment of the invention.

FIGS. 22A to 22C are schematic cross-sectional views by step sequencefollowing FIGS. 21A to 21C.

As shown in FIG. 20, the semiconductor light-emitting device 107according to the seventh embodiment of the invention is a specificexample of the semiconductor device 103 b according to the thirdembodiment. That is, the semiconductor light-emitting device 106 isprovided with the p-side transparent electrode 4 t between the p-sideelectrode 4 and the p-type semiconductor layer 2 in the semiconductorlight-emitting device 102 according to the second embodiment. Other thanthis, the semiconductor light-emitting device 107 is the same as thesemiconductor light-emitting device 102, and hence, the descriptionthereof will be omitted. Moreover, because the configuration and theeffect of the p-side transparent electrode 4 t have been described withrespect to the third embodiment, the description thereof will beomitted.

Moreover, in the semiconductor light-emitting device 107, the secondp-side electrode film 4 b and the second n-side electrode film 7 bhaving high-efficiency reflection characteristics are formedsimultaneously.

Hereinafter, the method for manufacturing the semiconductorlight-emitting device 107 according to this embodiment will bedescribed.

First, as shown in FIG. 21A, in the region of part of the p-typesemiconductor layer 2, until the n-type contact layer is exposed to thesurface, the p-type semiconductor layer 2 and the light-emitting layer 3are removed by dry etching using a mask.

Next, as shown in FIG. 21B, in order that the first n-side electrodefilm 7 a of the n-side electrode region having ohmic characteristics isformed, a patterned lift-off resist, which is not shown, is formed onthe semiconductor layer. And then, on the n-type contact layer, thefirst n-side electrode film 7 a made of, for example, Ti/Al/Ni/Au isformed with a film thickness of 500 nm, and sintered in a nitrogenatmosphere at 550° C.

As shown in FIG. 21C, to form the p-side transparent electrode 45 of thep-side electrode 4, a patterned lift-off resist, which is not shown, isformed on the semiconductor layer. And then, on the p-type contactlayer, using a vacuum deposition apparatus, for example, an indium tinoxide (ITO) layer serving as the p-side transparent electrode 4 t isformed with a film thickness of 100 nm.

To form the high-efficiency reflection regions of the p-side electrode 4and the n-side electrode 7 (second p-side electrode film 4 b and thesecond n-side electrode film 7 b), a lift-off resist is formed with anopening on the region of the n-type contact layer opposite to thetransparent electrode 4 t on the p-type contact layer with respect tothe first n-side electrode film 7 a that is an n-side electrode regionhaving ohmic characteristics and on the transparent electrode 4 t.

Here, considering the alignment accuracy of the pattern, part on then-side electrode (first n-side electrode film 7 a) having ohmiccharacteristics in the side facing the p-type contact layer may beopened.

Conversely, in order that the n-side electrode (second n-side electrodefilm 7 b) having high-efficiency reflection characteristics does notclimb up the n-side electrode (first n-side electrode film 7 a) havingohmic characteristics, the both electrodes may be designed with a slightspacing therebetween in considering the alignment accuracy of thepattern.

Furthermore, the n-side electrode (second n-side electrode film 7 b)having high-efficiency reflection characteristics may be designed so asto cover the part or the entirety of the n-side electrode (first n-sideelectrode film 7 a) having ohmic characteristics.

As shown in FIG. 22A, using a vacuum deposition apparatus, the secondp-side electrode film 4 b and the second n-side electrode film 7 b madeof, for example, Al/Ni/Au are formed with a film thickness of 300 nm.

Next, as shown in FIG. 22B, a patterned lift-off resist is formedlikewise on the semiconductor layer, and, for example, a Ti/Pt/Au layeris formed with a film thickness of 500 nm so as to coat the secondp-side electrode film 4 b, the entire high-efficiency reflection regionof the n-side electrode 7, and the part of the n-side electrode 7 havingohmic characteristics. Thereby, the first p-side electrode film 4 a andthe n-side pad 75 of the n-side electrode 7 are formed.

As shown in FIG. 22C, using a vacuum deposition apparatus, the total often layers of five pairs of combinations of SiO₂ and TiO₂ are formed onthe semiconductor. The thickness of each of the films is represented byλ/(4n) in which n is a refractive index of each of the dielectric layersand λ is an emission wavelength from the light-emitting layer 3.Thereon, a patterned resist is formed, and the dielectric material isremoved by ammonium fluoride treatment so that the p-side electrode 4and the n-side electrode 7 are exposed, and thereby, the dielectriclaminated film 11 is formed. The dielectric laminated film 11 may beformed by a lift-off method so that the p-side electrode 4 and then-side electrode 7 are exposed.

As described above, the semiconductor light-emitting device 107according to this embodiment can be fabricated.

In the semiconductor light-emitting device 107 according to thisembodiment, the high-efficiency reflection films of the p-side electrode4 and the n-side electrode 7 (second p-side electrode film 4 b andsecond n-side electrode film 7 b) can be formed simultaneously.Moreover, the first p-side electrode film 4 a of the p-side electrode 4and the n-side pad 75 of the n-side electrode 7 can be formedsimultaneously.

Thereby, the number of steps can be reduced, and the light generated inthe light-emitting layer can be taken out to the outside efficiently,and the semiconductor light-emitting device with high through-put andlow cost and the manufacturing method thereof can be provided.

Eighth Embodiment

FIG. 23 is a schematic cross-sectional view illustrating theconfiguration of the semiconductor light-emitting device according to aneighth embodiment of the invention.

FIGS. 24A to 24C are schematic cross-sectional views by step sequenceillustrating a method for producing the semiconductor light-emittingdevice according to the eighth embodiment of the invention.

FIG. 25 is a schematic cross-sectional view by step sequence followingFIGS. 24A to 24C.

As shown in FIG. 23, in the semiconductor light-emitting device 108according to the eighth embodiment of the invention, the first n-sideelectrode film 7 a and the n-side pad 75 in the semiconductorlight-emitting device 102 according to the second embodiment are usedtogether. Other than this, the semiconductor light-emitting device 108can be the same as the semiconductor light-emitting device 102, andhence, the description thereof will be omitted.

In the semiconductor light-emitting device 108, the second p-sideelectrode film 4 b and the second n-side electrode film 7 b havinghigh-efficiency reflection characteristics are formed simultaneously,and the first p-side electrode film 4 a and the first n-side electrodefilm 7 a and the n-side pad 75 can be formed simultaneously.

Hereinafter, the method for manufacturing the semiconductorlight-emitting device 108 according to this embodiment will bedescribed.

First, as shown in FIG. 24A, in the region of part of the p-typesemiconductor layer 2, until the n-type contact layer is exposed to thesurface, the p-type semiconductor layer 2 and the light-emitting layer 3are removed by dry etching using a mask.

Next, as shown in FIG. 24B, to form the high-efficiency reflectionregions of the p-side electrode 4 and the n-side electrode 7, a lift-offresist is formed with an opening on the regions of parts of the n-typecontact layer and the p-type contact layer, and using a vacuumdeposition apparatus, the second p-side electrode film 4 b and thesecond n-side electrode film 7 b made of, for example, Ag are formedwith a film thickness of 200 nm simultaneously, and sintered in anitrogen atmosphere at 350° C.

Furthermore, as shown in FIG. 24C, to form the first p-side electrodefilm 4 a of the p-side electrode 4 and the combination of the firstn-side electrode film 7 a of the n-side electrode 7 having ohmiccharacteristics and the n-side pad 75 of the n-side electrode 7, alift-off resist is formed with an opening on the region of the n-typecontact layer in the side facing the p-type contact layer with respectto the second n-side electrode film 7 b that is the n-side electroderegion having high efficiency reflection characteristics and the regionson the entirety of the first n-side electrode film 7 b and on the secondp-side electrode film 4 b. Using a vacuum deposition apparatus, thefirst p-side electrode film 4 a and combination of the first n-sideelectrode film 7 a and the n-side pad 75 made of, for example, Ti/Pt/Auare formed with a film thickness of 500 nm.

And, as shown in FIG. 25, using a vacuum deposition apparatus, the totalof ten layers of five pairs of combinations of SiO₂ and TiO₂ are formedon the semiconductor. The thickness of each of the films is representedby λ/(4n) in which n is a refractive index of each of the dielectriclayers and λ is an emission wavelength from the light-emitting layer 3.Thereon, a patterned resist is formed, and the dielectric material isremoved by ammonium fluoride treatment so that the p-side electrode 4and the n-side electrode 7 are exposed, and thereby, the dielectriclaminated film 11 is formed. The dielectric laminated film 11 may beformed by a lift-off method so that the p-side electrode 4 and then-side electrode 7 are exposed.

As described above, the semiconductor light-emitting device 108according to this embodiment can be fabricated.

In the semiconductor light-emitting device 108 according to thisembodiment, the high-efficiency reflection films of the p-side electrode4 and the n-side electrode 7 (second n-side electrode film 7 b) can beformed simultaneously. Moreover, the first p-side electrode film 4 a ofthe p-side electrode 4 and the combination of the first n-side electrodefilm and the n-side pad 75 of the n-side electrode 7 can be formedsimultaneously.

Thereby, the number of processes can be reduced, and the light generatedin the light-emitting layer can be taken out to the outside efficiently,and the semiconductor light-emitting device with high through-put andlow cost and the manufacturing method thereof can be provided.

Ninth Embodiment

FIG. 26 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aninth embodiment of the invention.

As shown in FIG. 26, the semiconductor light-emitting device 109according to the ninth embodiment of the invention is provided with ap-side pad 45 on the p-side electrode 4 in the semiconductorlight-emitting device 101 according to the first embodiment. Moreover,the n-side pad 75 is provided in the n-side electrode 7. Other thanthese, the semiconductor light-emitting device 109 can be the same asthe semiconductor light-emitting device 101 according to the firstembodiment, and hence, the description will be omitted.

That is, in the semiconductor light-emitting device 109, the p-side pad45 is provided so as to coat part or all on the p-side electrode 4. Forthe p-side pad 45, for example, a film of Au with a thickness of 200 nmcan be used.

Thereby, bondability is improved. Furthermore, heat-release from thesemiconductor light-emitting device can be improved.

The p-side pad 45 can also be used as a gold bump, and AuSn bump can beformed instead of Au.

Moreover, the p-side pad 45 may be provided so as to cover at least partof the dielectric laminated film 11 as well as part or entirety on thep-side electrode 4. Moreover, the p-side pad 45 and the n-side pad 75provided on the n-side electrode 7 can be formed simultaneously.

Moreover, in the case of separately providing the p-side 45 on thep-side electrode 4 for, bondability improvement of wire bonding, dieshare strength improvement in forming bold bump, flip chip mount, and soforth, the film thickness of the p-side pad 45 is not particularlylimited, but can be selected in the range of, for example, 100 nm to10000 nm.

As described above, in the semiconductor light-emitting device 109according to this embodiment, providing the p-side pad 45 (and n-sidepad 75) improves the bondability in the manufacturing process, and canprovide the semiconductor light-emitting device in which theheat-release is improved and the light generated in the light-emittinglayer can be taken out to the outside efficiently.

Tenth Embodiment

FIG. 27 is a schematic cross-sectional view illustrating theconfiguration of the semiconductor light-emitting device according to atenth embodiment of the invention.

As shown in FIG. 27, the semiconductor light-emitting device 110according to the tenth embodiment of the invention includes the p-sideelectrode 4 having the first p-side electrode film 4 a and the secondp-side electrode film 4 b described previously and further includes athird p-side electrode film (fifth metal film) 4 c provided between thefirst p-side electrode film 4 a and the second p-side electrode film 4 bby which the material composing the first p-side electrode film 4 a isprevented from diffusing to the second p-side electrode film 4 b, in thesemiconductor light-emitting device 101 according to the firstembodiment. Other than this, the semiconductor light-emitting device 110can be the same as the semiconductor light-emitting device 101 accordingto the first embodiment, and hence, the description thereof will beomitted.

The third p-side electrode film 4 c is provided between the secondp-side electrode film 4 b and the first p-side electrode film 4 a, andhas a function of preventing the first p-side electrode film 4 a fromdiffusing to or reacting with the second p-side electrode film 4 b. Forthe third p-side electrode film 4 c, a material that does not react withsilver or does not actively diffuse to silver can be used.

The third p-side electrode film 4 c can be based on a single-layer filmor laminated film of high melting point metal that can be used as thediffusion prevention layer such as vanadium (V), chromium (Cr), iron(Fe), cobalt (Co), nickel (Ni), niobium (Nb), molybdenum (Mo), ruthenium(Ru), rhodium (Rh), tantalum (Ta), tungsten (W), rhenium (Re), osmium(Os), iridium (Ir), or platinum (Pt).

For the third p-side electrode film 4 c, in order that there is noproblem if the material slightly diffuses to the second p-side electrodefilm 4 b, it is further preferable that as the metal having a high workfunction by which p-GaN contact layer and the ohmic property can beeasily obtained, iron (Fe), cobalt (Co), nickel (Ni), rhodium (Rh),tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), or platinum (Pt)is used.

It is preferable that the thickness of the third p-side electrode film 4c is 5 nm to 200 nm in which the film state can be held in the case of asingle-layer. In the case of a laminated film, the film thickness is notparticularly limited, but can be selected in the range of, for example,10 nm to 10000 nm.

As described above, according to the semiconductor light-emitting device110 according to this embodiment, the third p-side electrode film 4 ccan suppress diffusion or reaction between the first p-side electrodefilm 4 a and the second p-side electrode film 4 b, and hence thesemiconductor light-emitting device with the further higher electriccharacteristic and reliability can be provided and the light generatedin the light-emitting layer can be taken out to the outside efficiently.

Eleventh Embodiment

FIG. 28 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting device according to aneleventh embodiment of the invention.

As shown in FIG. 28, in the semiconductor light-emitting device 111according to the eleventh embodiment of the invention, the n-typesemiconductor layer 1 also has a taper-shaped portion 1 r in thesemiconductor light-emitting device 104 according to the fourthembodiment. And, therewith, the dielectric laminated film 11 obliquelycoats the taper-shaped portion 1 t of the laminated structure 1 s andthe taper-shaped portion 1 r of the n-type semiconductor layer 1. Otherthan this, the semiconductor light-emitting device 111 can be the sameas the semiconductor light-emitting device 104, and hence, thedescription thereof will be omitted.

In the semiconductor light-emitting device 111, the light emitted in thelight-emitting layer 3 repeats reflection at the interface ofsemiconductor—substrate having a large refractive index and the mainsurface 1 a in which the electrodes are formed, and is easily trapped inthe semiconductor layer. Some of the light is taken out of the deviceend face. However, in the semiconductor light-emitting device of squareor rectangle fabricated on a sapphire substrate, because all of the foursides are not cleaved surfaces, reproducibility of the device end faceshape is bad because of breaking the device, variations of the lightextraction efficiency of each of the devices and further the lightoutput thereof are caused.

In this case, according to the semiconductor light-emitting device 111according to this embodiment, forming the device end face side of thesemiconductor layer by wet etching or dry etching improves thereproducibility of the light path in the device end face side.Furthermore, by covering the device end face side of the semiconductorlayer with the dielectric laminated film 11, the emitted light isreflected to the substrate side, and thereby the light can be taken outefficiently.

As described above, in the semiconductor light-emitting device 111according to this embodiment, the light generated in the light-emittinglayer can be taken out to the outside further stably and moreefficiently.

Twelfth Embodiment

FIG. 29 is a schematic cross-sectional view illustrating theconfiguration of the semiconductor light-emitting device according to atwelfth embodiment of the invention.

FIGS. 30A to 30C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the twelfth embodiment of the invention.

FIG. 31A to 31C are schematic cross-sectional views by step sequencefollowing FIGS. 30A to 30C.

As shown in FIG. 29, the semiconductor light-emitting device 112according to the twelfth embodiment of the invention is provided withthe dielectric film 11 a described in the fifth embodiment and furtherprovided with the n-side pad 75 described in the second embodiment andthe p-side pad 45 described in the ninth embodiment in the semiconductorlight-emitting device 101 according to the first embodiment. However,ingenuity is made in the shapes of the dielectric film 11 a and thedielectric laminated film 11 and the n-side pad 75 and the p-side pad45, and thereby, as described later, the manufacture thereof becomessimpler and the process consistency is high.

That is, the semiconductor light-emitting device 112 further comprisesthe dielectric film 11 a provided between the dielectric laminated film11 and at least part of the n-side semiconductor layer 1 and the p-sidesemiconductor layer 2 being not covered with the n-side electrode 7 andthe p-side electrode 4.

Moreover, part of the dielectric film 11 a has a projecting portion thatis not covered with the dielectric laminated film 11, and on theprojecting portion, at least part of a conductive film connected to atleast any one of the first and second electrodes is provided. In thisspecific example, on the projecting portion, the n-side pad 75 connectedto the n-side electrode 7 and the p-side pad 45 connected to the p-sideelectrode 4 are provided, and the projecting portion is coated with then-side pad 75 connected to the n-side electrode 7 and the p-side pad 45connected to the p-side electrode 4.

Other than this, the semiconductor light-emitting device 112 can be thesame as the semiconductor light-emitting device 101, and the descriptionthereof will be omitted.

The n-side pad 75 and the p-side pad 45 can include at least any oneselected from the group consisting of Ru, Pt, and Pd, having highreflectance for the blue light or the light in the near-ultravioletregion. Thereby, the semiconductor light-emitting device in which thereflectance is enhanced particularly for the blue light or the light inthe near-ultraviolet region can be realized.

However, the invention is not limited thereto, but for the n-side pad 75and the p-side pad 45, an optional conductive material can be used. Alaminated film of the conductive film can also be used.

The semiconductor light-emitting device 112 according to this embodimentis manufactured, for example, as follows.

First, as shown in FIG. 30A, in the region of part of the p-typesemiconductor layer 2, until the n-type contact layer is exposed to thesurface, the p-type semiconductor layer 2 and the light-emitting layer 3are removed by dry etching by using a mask.

Next, as shown in FIG. 30B, using a thermal CVD apparatus, thedielectric film 11 a made of SiO₂ is formed on the semiconductor layerwith a film thickness of 100 nm. As described above, using a thermal CVDmethod, the dielectric film 11 a following the shape of step of thelaminated structure 1 s can be easily provided.

Next, as shown in FIG. 30C, on the SiO₂ serving as the dielectric film11 a, the dielectric laminated film 11 having a predetermined shape isformed. In this case, for the material of the dielectric laminated film11 and the forming method thereof, the methods described previously canbe used.

Next, as shown in FIG. 31A, after the SiO₂ of the dielectric film 11 ais partially removed by ammonium fluoride treatment, similarly, thesecond p-side electrode film 4 b is formed in a predetermined shape onthe p-type semiconductor layer 2 in the region in which the SiO₂ isremoved, and the first n-side electrode 7 a is formed in a predeterminedshape on part of the n-type semiconductor layer 1 in the region in whichthe SiO₂ is removed. For the material of the second p-side electrodefilm 4 b and the first n-side electrode film 7 a and the forming methodthereof, the methods described previously can be used.

Moreover, as shown in FIG. 31B, on part of the n-type semiconductorlayer 1 in the region in which the SiO₂ is removed, the second n-sideelectrode film 7 b is formed in a predetermined shape. For the materialof the second n-side electrode film 7 b and the forming method thereof,the methods described previously can be used.

As shown in FIG. 31C, on the p-type electrode layer 2 being not coveredwith the p-side electrode 4, the dielectric film 11 a and the dielectriclaminated film 11, a Ru film serving as the p-side pad 45 is formed.And, on the n-type semiconductor layer 1 being not covered with then-side electrode film 7 a and the second n-side electrode film 7 b andon the dielectric film 11 a and on the dielectric laminated film 11, aRu film serving as the n-side pad 75 is formed. In this case, by alift-off method, the formed Ru films can be processed to be in a shapeof the p-side pad 45 and the n-side pad 75. For the film to the p-sidepad 45 and the n-side pad 75, a metal such as Pt or Pd as well as Ru canbe used, and a conductive film except therefor can be used.

As described above, the semiconductor light-emitting device 112according to this embodiment can be formed.

The semiconductor light-emitting device 112 according to this embodimentcan provide the semiconductor light-emitting device in which bondabilityin the manufacturing process and the heat-release are improved and thelight generated in the light-emitting layer can be taken out to theoutside, because the n-side pad 75 and the p-side pad 45 are furtherprovided. Moreover, the formation of the p-side pad 45 and the n-sidepad 75 made of, for example, Ru film can be formed at one time, and theprocesses can be omitted.

Furthermore, because the dielectric laminated film 11 is processedbefore forming the n-side electrode 7 (first n-side electrode film 7 aand second n-side electrode film 7 b) and the p-side electrode 4, theprocess consistency is high and the manufacture thereof is easy.

That is, the dielectric laminated film 11 is formed by, for example, alift-off method, and then, the dielectric film 11 a is processed by, forexample, a wet etching method or a dry etching method. And, on theexposed first and second semiconductor layers, the n-side electrode 7and the p-side electrode 4 are formed by, for example, a lift-offmethod, respectively. Thereby, the process consistency is improved andthe process margin is enlarged.

Thirteenth Embodiment

FIG. 32 is a schematic cross-sectional view illustrating theconfiguration of the semiconductor light-emitting device according to athirteenth embodiment of the invention.

FIGS. 33A to 33C are schematic cross-sectional views by step sequenceillustrating a method for manufacturing the semiconductor light-emittingdevice according to the thirteenth embodiment of the invention.

FIG. 34A to 34C are schematic cross-sectional views by step sequencefollowing FIGS. 33A to 33C.

As shown in FIG. 32, the semiconductor light-emitting device 113according to the thirteenth embodiment of the invention is provided withthe dielectric film 11 a described in the fifth embodiment and furtherprovided with the taper-shaped portion 1 t of the laminated structure isdescribed in the fourth embodiment in the semiconductor light-emittingdevice 101 according to the first embodiment. However, ingenuity is madein the shapes of the dielectric film 11 a, the dielectric laminated film11, the first and second n-side electrode films 7 a, 7 b, and the firstand second p-side electrode films 4 a, 4 b, and as described later, themanufacture thereof is simpler.

That is, the semiconductor light-emitting device 113 further comprisesthe dielectric film 11 a provided between the dielectric laminated film11 and at least part of the n-side semiconductor layer 1 and the p-sidesemiconductor layer 2 being not covered with the n-side electrode 7 andthe p-side electrode 4.

Moreover, the dielectric film 11 a has a projecting portion that is notcovered with the dielectric laminated film 11, and on the projectingportion, at least part of at least any one of the n-side electrode 7 andthe p-side electrode 4 is provided. In this specific example, on theprojecting portion, the first p-side electrode film 4 a that is part ofthe p-side electrode 4 is provided, and the projecting portion is coatedwith the first p-side electrode film 4 a that is part of the p-sideelectrode 4.

Other than this, the semiconductor light-emitting device 113 can be thesame as the semiconductor light-emitting device 101, and hence, thedescription thereof will be omitted.

The semiconductor light-emitting device 113 according to this embodimentis manufactured by, for example, the following method.

First, as shown in FIG. 33A, in the region of part of the p-typesemiconductor layer 2, until the n-type contact layer is exposed to thesurface, the p-type semiconductor layer 2 and the light-emitting layer 3are removed by dry etching by using a mask.

Next, as shown in FIG. 33B, using a thermal CVD apparatus, thedielectric film 11 a made of SiO₂ is formed on the semiconductor layerwith a film thickness of 100 nm. As described above, using a thermal CVDmethod, the dielectric film 11 a following the shape of the taper-shapedportion 1 t of the laminated structure is can be easily provided.

Next, as shown in FIG. 33C, on the SiO₂ serving the dielectric film 11a, the dielectric laminated film 11 having a predetermined shape isformed. In this case, for the material of the dielectric laminated film11, a laminated film of TiO/(SiO/TiO)₄ can be used. For the filmformation of this laminated film, as described previously, a vacuumdeposition method can be used, and for the processing of the shape, alift-off method can be used.

In the laminated film made of TiO/(SiO/TiO)₄ serving as the dielectriclaminated film 11, the thickness of each of the films is represented byλ/(4n) in which n is a refractive index of each of the dielectric layersand λ is an emission wavelength from the light-emitting layer 3.

Next, as shown in FIG. 34A, after the SiO₂ serving as the dielectricfilm 11 a is partially removed by ammonium fluoride treatment, thesecond p-side electrode film 4 b is formed in a predetermined shape onthe p-type semiconductor layer 2 in the region in which the SiO₂ isremoved, and the first n-side electrode 7 a is formed in a predeterminedshape on part of the n-type semiconductor layer 1 in the region in whichthe SiO₂ is removed. For the material of the second p-side electrodefilm 4 b and the first n-side electrode film 7 a, the previouslydescribed material can be used, and for the forming method thereof, thelift-off method described previously can be used.

As shown in FIG. 34B, on part of the n-type semiconductor layer 1 in theregion in which the SiO₂ is removed, the second n-side electrode film 7b is formed in a predetermined shape. For the material of the secondn-side electrode film 7 b, the previously described material can beused, and for the forming method thereof, the lift-off method describedpreviously can be used.

Moreover, as shown in FIG. 34C, the first p-side electrode 4 a is formedso as to cover the entire surface of the second p-side electrode film 4b and the p-type semiconductor layer 2 being not covered with the secondp-side electrode film 4 b. For the material of the first p-sideelectrode film 4 a, the previously described material can be used, andfor the forming method thereof, the lift-off method described previouslycan be used.

As described above, the semiconductor light-emitting device 113according to this embodiment can be formed.

In the semiconductor light-emitting device 113 according to thisembodiment, the laminated structure 1 s has the taper-shaped portion 1 tand hence the reflection characteristics are further higher.

Furthermore, the dielectric laminated film 11 is processed beforeforming the n-side electrode 7 (first n-side electrode film 7 a andsecond n-side electrode film 7 b) and the p-side electrode 4, theprocess consistency is high and the production thereof is easy.

That is, the dielectric laminated film 11 is formed by, for example, alift-off method, and then, the dielectric film 11 a is processed by, forexample, a wet etching method or a dry etching method. And, on theexposed first and second semiconductor layers, the n-side electrode 7and the p-side electrode 4 are formed by, for example, a lift-offmethod, respectively. Thereby, the process consistency is improved andthe process margin is enlarged.

As described above, the semiconductor light-emitting device 113according to this embodiment can provide the semiconductorlight-emitting device by which the light generated in the light-emittinglayer is taken out to the outside efficiency and that can be easilymanufactured and the manufacturing method thereof.

In the semiconductor light-emitting device 113 according to thisembodiment, after the process illustrated in FIG. 34C, the p-side pad 45and the n-side pad 75 described in the twelfth embodiment may beprovided. In this case, the structure is such that the dielectric film11 a has a projecting portion that is not covered with the dielectriclaminated film 11, and on the projecting portion, at least part of theconductive film connected to at least any one of the first and secondelectrodes is provided.

Fourteenth Embodiment

FIG. 35 is a flow chart illustrating a method for manufacturing asemiconductor light-emitting device according to a fourteenth embodimentof the invention.

As shown in FIG. 35, in the method for manufacturing the semiconductorlight-emitting device according to the fourteenth embodiment of theinvention, first on the substrate 10, the first semiconductor layer(n-type semiconductor layer 1), the light-emitting layer 3 and thesecond semiconductor layer (p-type semiconductor layer 2) are laminatedand formed (Step S110). For this, for example, the method described withregard to the first embodiment can be used.

Part of the second semiconductor layer and the light-emitting layer areremoved to expose the first semiconductor layer (Step S120). For this,for example, the method described with regard to the second embodimentcan be used.

On the first region of the exposed first semiconductor layer, a firstmetal film (first n-side electrode film 7 a) is formed (Step S130). Forthis, for example, the method described with regard to the secondembodiment can be used.

On a second region adjacent to the first region of the exposed firstsemiconductor layer and on the second semiconductor layer, a secondmetal film (second n-side electrode film 7 b and second p-side electrodefilm 4 b) that have a higher reflectance for light emitted from thelight-emitting layer 3 than the first metal film and that has a highercontact resistance with respect to the first semiconductor layer thanthe first metal film are formed (Step S140). For this, for example, themethod described with regard to the sixth embodiment can be used.

Furthermore, on the first semiconductor layer and the secondsemiconductor layer that are not covered with the first metal film andthe second metal film, a dielectric laminated film in which a pluralityof kinds of dielectric films having different refractive indices arealternately laminated is formed (Step S150). For this, for example, themethod described with regard to the second embodiment can be used.

According to the method for manufacturing the semiconductorlight-emitting device according to this embodiment, the second p-sideelectrode film 4 b having high-efficiency reflection characteristics ofthe p-side electrode 4 and the second n-side electrode film 7 b havinghigh-efficiency reflection characteristics are composed of the samematerial, and can be formed simultaneously.

Thereby, the number of processes can be reduced, and the light generatedin the light-emitting layer can be taken out to the outside efficiently,and the method for manufacturing the semiconductor light-emitting devicewith high through-put can be provided.

The above Steps S110 to S150 can be interchanged in the technicallypossible range, or can be carried out simultaneously.

Fifteenth Embodiment

FIG. 36 is a flow chart illustrating a method for manufacturing asemiconductor light-emitting device according to a fifteenth embodimentof the invention.

As shown in FIG. 36, in the method for manufacturing the semiconductorlight-emitting device according to the fifteenth embodiment of theinvention, first on the substrate 10, the first semiconductor layer(n-type semiconductor layer 1), the light-emitting layer 3, and thesecond semiconductor layer (p-type semiconductor layer 2) are laminatedand formed (Step S210). For this, for example, the method described withregard to the first embodiment can be used.

Part of the second semiconductor layer and the light-emitting layer areremoved to expose the first semiconductor layer (Step 220). For this,for example, the method described with regard to the second embodimentcan be used.

On the first semiconductor layer and the second semiconductor layer, thedielectric laminated film 11 in which a plurality of kinds of dielectricfilms having different refractive indices are laminated is formed (Step230). For this, for example, the method described with regard to thesecond embodiment can be used.

On the first region of the first semiconductor layer being not coveredwith the dielectric laminated film, the first metal film (first n-sideelectrode film 7 a) is formed, and on the second region of the firstsemiconductor layer that is not covered with the dielectric laminatedfilm 11 and that is adjacent to the first region, a second metal film(second n-side electrode film 7 b) that has a higher reflectance forlight emitted from the light-emitting layer than the first metal filmand that has a higher contact resistance with respect to the firstsemiconductor layer than the first metal film is formed (Step S240). Forthis, for example, the method described with regard to the secondembodiment can be used.

As described above, in the method for manufacturing the semiconductorlight-emitting device according to this embodiment, before forming thefirst metal film (first n-side electrode film 7 a) and the second metalfilm (second n-side electrode film 7 b), the dielectric laminated film11 is provided. That is, this is the order of steps in the methods formanufacturing the semiconductor light-emitting devices according to thetwelfth and thirteenth embodiments.

According to experiments by the inventors, when the dielectric laminatedfilm 11 is formed using a vacuum deposition apparatus at roomtemperature, the etching rate by wet etching is very rapid, and theworkability of the film is low. Moreover, if high-temperature heattreatment is performed during or after the film formation, the wetetching rate becomes very small for zirconium oxide or titanium oxide orthe like, and processing of the film becomes difficult. Therefore, thedielectric laminated film 11 can be processed by, for example, alift-off method.

In this case, by providing the dielectric laminated film 11 beforeforming the first metal film (first n-side electrode film 7 a) and thesecond metal film (second n-side electrode film 7 b), the processconsistency is enhanced and the margin of the production is enlarged.

As described above, the method for manufacturing the semiconductorlight-emitting device according to this embodiment can provide themethod for manufacturing the semiconductor light-emitting device inwhich the process consistency is high and that is easily fabricated andin which the light generated in the light-emitting layer can be takenout to the outside efficiently.

FIG. 37 is a flow chart showing a modified example of the method formanufacturing the semiconductor light-emitting device according to thefifteenth embodiment of the invention.

As shown in FIG. 37, in the modified example of the method formanufacturing the semiconductor light-emitting device according to thefifteenth embodiment of the invention, between the exposure process ofthe first semiconductor layer (Step S220) and the formation process ofthe dielectric laminated film 11 (Step S230), the dielectric film 11 ahaving higher step coverage characteristics on the first semiconductorlayer and the second semiconductor layer than the dielectric laminatedfilm 11 is formed on the first semiconductor layer and the secondsemiconductor layer (Step S225).

For this dielectric film 11 a, as explained in the thirteenthembodiment, for example, a SiO₂ film formed by a thermal CVD method canbe used.

That is, the formation of the dielectric film 11 a can be carried out bya chemical vapor deposition method.

Thereby, the dielectric film 11 a having high step coveragecharacteristics on the first semiconductor layer and the secondsemiconductor layer can be formed.

And, as described with regard to the thirteenth embodiment, after theformation of the dielectric film 11 a, the formation of the dielectriclaminated film 11 is performed by, for example, a lift-off method, andthen the dielectric film 11 a is processed by, for example, a wetetching method or a dry etching method. And, on the exposed first andsecond semiconductor layers, the n-side electrode 7 and the p-sideelectrode 4 are formed, respectively.

In the method for manufacturing the semiconductor light-emitting deviceaccording to this embodiment, as described in fifth embodiment, beforeforming the first n-side electrode film 7 a and the second p-sideelectrode film 4 b, the dielectric film 11 a is formed on thesemiconductor layer, and hence, contamination attaching to the interfacebetween the electrode and the semiconductor layer in theelectrode-forming process can be drastically reduced, and therefore,reliability, yield, electric characteristic, and optical characteristicscan be improved.

According to the method for manufacturing the semiconductorlight-emitting device of the modified example of this embodiment, therecan be provided the method for manufacturing the semiconductorlight-emitting device in which the process consistency is high, andreliability, yield, electric characteristics, and opticalcharacteristics are high.

Sixteenth Embodiment

FIG. 38 is a schematic cross-sectional view illustrating theconfiguration of a semiconductor light-emitting apparatus according to asixteenth embodiment of the invention.

The semiconductor light-emitting apparatus 201 according to thesixteenth embodiment of the invention is a white LED in which any one ofthe above semiconductor light-emitting devices according to therespective embodiments and a fluorescent material are combined.Hereinafter, the case that the semiconductor light-emitting device 101according to the first embodiment and a fluorescent material arecombined will be described.

That is, the semiconductor light-emitting apparatus 201 according tothis embodiment comprises any one of the semiconductor light-emittingdevices described above and a fluorescent material layer irradiated withthe light emitted in the semiconductor device.

As shown in FIG. 38, in the semiconductor light-emitting apparatus 201according to this embodiment, a reflection film 23 is provided on theinner surface of a container 22 made of ceramic or the like. Thereflection film 23 is provided so as to be divided into the inner sidesurface and the bottom surface of the container 22. The reflection film23 is made of, for example, aluminum or the like. On the reflection film23 provided on the bottom surface of the container 22, the semiconductorlight-emitting device 101 illustrated in FIG. 1 is disposed through asubmount 24.

On the semiconductor light-emitting device 101, gold bumps 25 are formedby a ball bonder, and the semiconductor light-emitting device 101 isfixed to the submount 24. It is also possible that without using thegold bump 25, the semiconductor light-emitting device 101 is directlyfixed to the submount 24.

Adhesive bonding by an adhesive agent or soldering or the like can beused to fix the semiconductor light-emitting device 101, the submount24, and the reflection film 23.

On the surface of the semiconductor light-emitting device side of thesubmount 24, patterned electrodes are formed so that the p-sideelectrode 4 and the n-side electrode 7 of the semiconductorlight-emitting device 101 are insulated, and the respective patternedelectrodes are connected to the electrodes (not shown) provided in thecontainer 22 side, with bonding wires 26. The connections are formedbetween the reflective film 23 on the inner side surface and thereflective film 23 on the bottom surface.

Moreover, a first fluorescent material layer 211 containing a redfluorescent material is provided so as to cover the semiconductorlight-emitting device 101 and the bonding wires 26. On the firstfluorescent material layer 211, a second fluorescent material layer 212containing a blue, green, or yellow fluorescent material is formed. Onthis fluorescent material layer, a lid 27 made of silicon resin isprovided.

The first fluorescent material layer 211 contains a resin and a redfluorescent material dispersed in the resin.

For the red fluorescent material, for example, Y₂O₃, YVO₄, Y₂(P,V)O₄ orthe like can be used as the parent material, and trivalent Eu (Eu³⁺) iscontained therein as the activation substance. That is, Y₂O₃:Eu³⁺,YVO₄:Eu³⁺, or the like can be used as the red fluorescent material. Theconcentration of Eu³⁺ can be 1% to 10% in terms of molarity. As theparent material of the red fluorescent material, as well as Y₂O₃ orYVO₄, LaOS or Y₂(P,V)O₄ or the like can be used. Moreover, as well asEu³⁺, Mn⁴⁺ or the like can be utilized. In particular, by adding a smallamount of Bi with the trivalent Eu to the parent material of YVO₄, theabsorption at 380 nm increases, and therefore, the light-emittingefficiency can be further enhanced. Moreover, as the resin, for example,silicone resin or the like can be used.

Moreover, the second fluorescent material layer 212 contains a resin andat least any one of blue, green, and yellow fluorescent materialsdispersed in the resin. For example, the fluorescent material combiningthe blue fluorescent material and the green fluorescent material may beused, or the fluorescent material combining the blue fluorescentmaterial and the yellow fluorescent material may be used, or thefluorescent material combining the blue fluorescent material, the greenfluorescent material, and the yellow fluorescent material may be used.

For the blue fluorescent material, for example, (Sr,Ca)₁₀(PO₄)₆Cl₂:Eu²⁺or BaMg₂Al₁₆O₂₇:Eu²⁺ or the like can be used.

For the green fluorescent material, for example, Y₂SiO₅:Ce³⁺,Tb³⁺ withtrivalent Tb serving as the emission center can be used. In this case,because the energy is transferred from the Ce ion to the Tb ion, theexcitation efficiency is enhanced. For the green fluorescent material,for example, Sr₄Al₁₄O₂₅:Eu²⁺ or the like can be used.

For the yellow fluorescent material, for example, Y₃Al₅:Ce³⁺ or the likecan be used.

Moreover, for the resin, for example, silicone resin or the like can beused.

In particular, trivalent Tb exhibits sharp emission in the vicinity of550 nm where the visibility is maximized, and hence, when trivalent Tbis combined with the sharp red emission of trivalent Eu, the emissionefficiency is significantly enhanced.

By the semiconductor light-emitting apparatus 201 according to thisembodiment, the ultraviolet light of 380 nm generated from thesemiconductor light-emitting device 101 is emitted toward the substrate10 of the semiconductor light-emitting device 101, and the reflection atthe reflection film 23 is also utilized, and thereby, the abovefluorescent materials contained in the respective fluorescent materiallayers can be efficiently excited.

For example, in the above fluorescent material having the emissioncenter of trivalent Eu or the like contained in the first fluorescentmaterial layer 211, the light is converted into light having a narrowwavelength distribution in the vicinity of 620 nm, and thereby, the redvisible light can be efficiently obtained.

Moreover, the blue, green, or yellow fluorescent materials contained inthe second fluorescent material layer 212 are efficiently excited, andthereby, the blue, green, or yellow visible light can be efficientlyobtained.

As the mixed colors thereof, white light and light with various othercolors can be obtained with high efficiency and good color rendition.

Next, the method for manufacturing the semiconductor light-emittingapparatus 201 according to this embodiment will be described.

For the processes for fabricating the semiconductor light-emittingdevice 101, the previously described method can be used, and hence,hereinafter, the processes after the semiconductor light-emitting device101 is completed will be described.

First, the metal film serving as the reflection film 23 is formed on theinner surface of the container 22 by, for example, sputtering, and themetal film is patterned to leave the reflection films 23 on the bottomsurface and the inner side surface of the container 22, respectively.

Next, on the semiconductor light-emitting device 101, the gold bumps 25are formed by a ball bonder. And, on the submount 24 having theelectrodes patterned for the p-side electrode 4 and the n-side electrode7, the semiconductor light-emitting device 101 is fixed, and thesubmount 24 is disposed and fixed onto the reflection film 23 on thebottom surface of the container 22. To fix them, adhesive bonding by anadhesive agent or soldering or the like can be used. Moreover, it isalso possible that without using the gold bump 25 by the ball bonder,the semiconductor light-emitting device 101 is directly fixed onto thesubmount 24.

Next, the n-side electrode and p-side electrode (not shown) on thesubmount 24 are connected to the electrodes (not shown) provided on thecontainer 22 side, respectively, with bonding wires 26.

Furthermore, the first fluorescent material layer 211 containing the redfluorescent material is formed so as to cover the semiconductorlight-emitting device 101 and the bonding wires 26, and the secondfluorescent material layer 212 containing blue, green or yellowfluorescent material is formed on the first fluorescent material layer211.

For the respective methods for forming the fluorescent material layers,for example, a method of dropping each of the fluorescent materialsdispersed in a resin raw material mixture and then performing thermalpolymerization by heat treatment to cure the resin can be used. When theresin raw material mixture containing each of the fluorescent materialsis dropped and then left to stand for a while and then cured, the fineparticles of each of the fluorescent materials are precipitated and thefine particles can be localized to the lower portions of the first andsecond fluorescent layers 211, 212, and thereby, the emission efficiencyof each of the fluorescent materials can be appropriately controlled.Then, the lid 27 is provided on the fluorescent material layer, andthereby, the semiconductor light-emitting apparatus 201 according tothis embodiment, namely, a white LED is fabricated.

In this specification, “nitride semiconductor” includes all of thesemiconductors having the compositions in which the composition ratiosx, y, and z are changed in the respective ranges in the chemical formulaof B_(x)In_(y)Al_(z)Ga_(1-x-y-z)N (0≦x≦1, 0≦y≦1, 0≦z≦1, x+y+z≦1).Furthermore, in the above chemical formula, the semiconductor furthercontaining the group V element other than N (nitrogen) or thesemiconductor further containing any one of various dopants to be addedfor controlling the conductivity type and so forth is also included inthe “nitride semiconductor”.

As described above, the embodiments of the invention have been describedwith reference to the specific examples. However, the invention is notlimited to these specific examples. For example, for shape, size,material, and disposition relation of each of the components such as thesemiconductor multilayer film, the metal film, and the dielectric filmconstituting the semiconductor light-emitting device, and formanufacturing methods thereof, such inventions are included in the scopeof the invention as long as the inventions can be similarly carried outby performing appropriate selection from the known range by thoseskilled in the art and the same effect can be obtained.

Moreover, combinations of two or more components of each of the specificexamples in the technically possible range are included in the scope ofthe invention as long as including the spirit of the invention.

In addition, all of the semiconductor light-emitting devices and themethods for manufacturing the same which can be carried out withappropriately design-modified by those skilled in the art based on thesemiconductor light-emitting device and the method for manufacturing thesame that have been described as the embodiments of the invention alsobelong to the scope of the invention as long as including the spirit ofthe invention.

In addition, it is conceived that in the range of the idea of theinvention, various variations and modifications can be achieved by thoseskilled in the art and it is understood that such variations andmodifications also belong to the scope of the invention.

1. A semiconductor light-emitting device comprising: a laminatedstructure including, a first semiconductor layer, a second semiconductorlayer, and a light-emitting layer provided between the firstsemiconductor layer and the second semiconductor layer, the secondsemiconductor layer and the light-emitting layer being selectivelyremoved and a part of the first semiconductor layer being exposed to afirst main surface on a side of the second semiconductor layer; a firstelectrode provided on the first main surface of the laminated structureand connected to the first semiconductor layer and having a first regionincluding a first metal film provided on the part of the firstsemiconductor layer and a second region including a second metal filmprovided on the part of the first semiconductor layer, the second regionhaving a higher reflectance for light emitted from the light-emittinglayer than the first metal film and the second region having a highercontact resistance with respect to the first semiconductor layer thanthe first metal film; a second electrode provided on the first mainsurface of the laminated structure and connected to the secondsemiconductor layer; and a dielectric laminated film provided on asurface of the first semiconductor layer and the second semiconductorlayer, the surface being not covered with any one of the first electrodeand the second electrode on the first main surface, the dielectriclaminated film having a plurality of dielectric films having differentrefractive indices being laminated.